embodied energy and carbon footprint of household...

Embodied Energy and Carbon Footprint of Household Latrines in Rural Peru:

The Impact of Integrating Resource Recovery

by

Christopher Galvin

A thesis submitted in partial fulfillment of the requirements for the degree of

Master of Science in Environmental Engineering Department of Civil and Environmental Engineering

College of Engineering University of South Florida

Major Professor: James R. Mihelcic, Ph.D. Qiong Zhang, Ph.D. Daniel Yeh, Ph.D.

Date of Approval: April 3, 2013

Keywords: Life Cycle Assessment, Sustainable Development, Sanitation, Anaerobic Biodigestion, Global Warming

Copyright © 2013, Christopher Galvin

ACKNOWLEDGMENTS

I would like to take this opportunity to thank the following people and institutions that

were instrumental in the completion of this project:

The University of South Florida and the United States Peace Corps, my advisor and

committee members, Dr. James Mihelcic, Dr. Qiong Zhang, and Dr. Daniel Yeh, Pablo Cornejo,

Christine Prouty, Michael MacCarthy, the wonderful people of Santo Domingo, Peru for allowing

me to be part of their small community for two years, and my family for their support and

understanding.

This material is based upon work supported by the National Science Foundation under

Grant No. 0965743. Any opinions, findings, and conclusions or recommendations expressed in

this material are those of the author(s) and do not necessarily reflect the views of the National

Science Foundation.

i

TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................... iii LIST OF FIGURES ..................................................................................................................... v ABSTRACT ................................................................................................................................ vi CHAPTER 1: INTRODUCTION .................................................................................................. 1 1.1 Research Motivation .................................................................................................. 1 1.2 Objective and Hypotheses ......................................................................................... 4 CHAPTER 2: PREVIOUS RESEARCH AND BACKGROUND INFORMATION .......................... 6 2.1 Nutrient Content of Human Excreta ........................................................................... 6 2.2 Anaerobic Digestion .................................................................................................. 7 2.3 Pathogen Destruction in Composting Latrines ........................................................... 9 2.4 Life Cycle Assessments Related to Water and Wastewater ..................................... 13 2.5 Sanitation Technologies Evaluated in this Study ...................................................... 15 2.5.1 Ventilated Improved Pit Latrine ................................................................. 15 2.5.2 Composting Latrine ................................................................................... 17 2.5.3 Pour-Flush Latrine ..................................................................................... 18 2.5.4 Biodigester Latrine .................................................................................... 19 CHAPTER 3: METHODS ......................................................................................................... 22 3.1 Goal and Scope Definition ....................................................................................... 22 3.2 Site Location ............................................................................................................ 22 3.3 Defining the Functional Unit and System Boundary ................................................. 24 3.3.1 Data Collection and Life Cycle Inventory ................................................... 27 3.4 Calculations for Life Cycle Inventory ........................................................................ 29 3.4.1 Material Production ................................................................................... 29 3.4.2 Material Delivery ....................................................................................... 30 3.4.3 Biochemical Oxygen Demand Input .......................................................... 31 3.4.4 Anaerobic Degradation of Domestic Wastewater ...................................... 32 3.4.5 Aerobic Degradation of Domestic Wastewater .......................................... 32 3.4.6 Biogenic Emissions ................................................................................... 33 3.4.7 Resource Recovery through Biogas and Nutrients .................................... 36 3.4.7.1 Biogas ........................................................................................ 36 3.4.7.2 Biodigester Effluent..................................................................... 36 3.4.7.3 Compost and Urine Diversion ..................................................... 37 3.5 Sensitivity Analysis .................................................................................................. 37 3.6 Life Cycle Impact Assessment and Interpretation .................................................... 38 CHAPTER 4: RESULTS AND DISCUSSION ........................................................................... 39 4.1 Impact of Privacy Structure on CED and GWP ........................................................ 39

4.2 CED and GWP Associated with Use Phase and Resource Recovery ...................... 45 4.3 CED and GWP of Household and Community-Level Sanitation Systems ................ 51

ii

4.4 Sensitivity Analysis .................................................................................................. 55 CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH....... 59 REFERENCES ......................................................................................................................... 62 APPENDICES ........................................................................................................................... 68 Appendix A Material Inventories .................................................................................... 69 Appendix B LCA Results Data ....................................................................................... 83 Appendix C Permissions ............................................................................................... 92 C.1 Cairncross and Feachem (1993) Permission ............................................... 92 C.2 Buckley et al. (2008) Permission ................................................................. 92 C.3 Mihelcic et al. (2009) Permission ................................................................. 92

iii

LIST OF TABLES Table 1: Burden of diarrheal disease by global region, 2000 ....................................................... 2 Table 2: Characteristics of daily human excreta per person ........................................................ 6 Table 3: Nutrient concentrations of potential biodigester feeds ................................................... 8 Table 4: Microbiological analysis of five samples obtained from active compost latrines in

Panama ...................................................................................................................... 12 Table 5: Chemical composition of compost samples ................................................................. 13 Table 6: Embodied energy of eight water supply interventions in Mali ....................................... 15 Table 7: Basic characteristics of the four latrine technologies considered in this study.............. 24 Table 8: Model input data collected and SimaPro inputs ........................................................... 29 Table 9: Distances to site location from material origins ............................................................ 31 Table 10: Biogenic emissions associated with each system ...................................................... 36 Table 11: Latrine design variations considered in this study ...................................................... 40 Table 12: Cumulative energy demand of latrine components for construction phase ................ 43 Table 13: Global warming potential of latrine components for construction phase ..................... 44 Table 14: Contributions to cumulative energy demand of four sanitation systems that

consider resource recovery over 20-year life. ............................................................ 46 Table 15: Contributions to global warming potential of sanitation systems over 20-year life ...... 49 Table 16: Sensitivity factors for privacy shelter (construction phase) results ............................. 57 Table 17: Sensitivity factors for construction and use phase results .......................................... 58 Table A.1: Material inventory for VIP latrine adobe fiber cement privacy structure .................... 69 Table A.2: Material inventory for VIP latrine brick corrugated metal privacy structure................ 70 Table A.3: Material inventory for VIP latrine adobe fiber cement privacy structure

(unlined pit) .............................................................................................................. 71

iv

Table A.4: Material inventory for pour-flush latrine adobe fiber cement privacy structure .......... 72 Table A.5: Material inventory for pour-flush latrine brick corrugated metal privacy structure...... 73 Table A.6: Material inventory for composting latrine adobe fiber cement privacy structure ........ 75 Table A.7: Material inventory for composting latrine brick corrugated metal privacy structure ... 76 Table A.8: Material inventory for biodigester latrine adobe fiber cement privacy structure ......... 78 Table A.9: Material inventory for biodigester latrine brick corrugated metal privacy structure .... 80 Table B.1: LCA results for construction and use phase of VIP latrine adobe fiber cement

privacy structure ...................................................................................................... 83 Table B.2: LCA results for construction phase of VIP latrine brick corrugated metal privacy

structure .................................................................................................................. 84 Table B.3: LCA results for construction phase of VIP latrine adobe fiber cement (unlined pit)

privacy structure ...................................................................................................... 85 Table B.4: LCA results for construction and use phase of pour-flush latrine adobe

fiber cement privacy structure .................................................................................. 86 Table B.5: LCA results for construction phase of pour-flush latrine brick corrugated

metal privacy structure ............................................................................................. 87 Table B.6: LCA results for construction and use phase of composting latrine adobe

fiber cement privacy structure .................................................................................. 88 Table B.7: LCA results for construction phase of composting latrine brick corrugated metal

privacy structure ...................................................................................................... 89 Table B.8: LCA results for construction and use phase of biodigester latrine adobe

fiber cement privacy structure .................................................................................. 90 Table B.9: LCA results for biodigester latrine brick corrugated metal privacy structure .............. 91

v

LIST OF FIGURES Figure 1: Access to water and sanitation statistics and child mortality rates for Peru .................. 3 Figure 2: The influence of time and temperature on a variety of excreted pathogens ................ 11 Figure 3: Components of a VIP latrine ...................................................................................... 17 Figure 4: Two-vault composting latrine ...................................................................................... 18 Figure 5: Pour-flush latrine with off-set collection pit.................................................................. 19 Figure 6: Diagram of Taiwanese style household biodigester latrine ......................................... 20 Figure 7: Photo of Taiwanese style biodigester installed in Santo Domingo, Piura, Peru .......... 21 Figure 8: Location of study site in Piura, Peru ........................................................................... 23 Figure 9: System diagram showing the inputs and outputs for: (a) VIP latrine (b) pour-flush

latrine (c) composting latrine and (d) biodigester latrine ............................................ 26 Figure 10: LCA framework used in this study for materials associated with the four

household sanitation technologies ........................................................................... 28 Figure 11: Diagram of VIP latrine showing different theoretical layers ....................................... 35 Figure 12: (a) Cumulative energy demand and (b) global warming potential of construction

phase of sanitation systems ..................................................................................... 41 Figure 13: Cumulative energy demand of four sanitation systems over a 20-year period (a)

without resource recovery and (b) with resource recovery ....................................... 45 Figure 14: Global warming potential of four sanitation systems over a 20-year period (a)

without resource recovery and (b) with resource recovery ....................................... 48 Figure 15: Contribution of materials and biogenic emissions to global warming potential

for each sanitation system ....................................................................................... 50 Figure 16: Cumulative energy demand of household and community level sanitation systems per household over 20-year period (a) without resource recovery and (b) with resource recovery ....................................................................................... 52 Figure 17: Global warming potential of household and community level sanitation systems per household over 20-year period (a) without resource recovery and (b) with

resource recovery .................................................................................................... 53

vi

ABSTRACT

Over seventy percent of the 2.5 billion people who still lack access to basic sanitation

worldwide live in rural areas (WHO/UNICEF, 2012). Despite concerns of water scarcity,

resource depletion, and climate change little research has been conducted on the

environmental sustainability of household sanitation technologies common in rural areas of

developing countries or the potential of resource recovery to mitigate the environmental impacts

of these systems. The environmental sustainability, in terms of embodied energy and carbon

footprint, was analyzed for four household sanitation systems: (1) Ventilated Improved Pit (VIP)

latrine, (2) pour-flush latrine, (3) composting latrine, and (4) biodigester latrine. Variations in

design and construction materials used change the embodied energy of the systems. It was

found that systems that used clay brick in the construction of the superstructure had an average

cumulative energy demand 4,307 MJ and a global warming potential 362 kilograms of

greenhouse gas equivalent (kgCO2 eq) higher than systems that used adobe brick in the

construction of the superstructure. It was also found that systems that incorporate resource

recovery, such as a composting or biodigester latrine, can become net energy producers over

their service life, recovering between 29,333 and 253,190 MJ over a 20-year period, compared

to the 11,275 to 19,990 MJ required for their construction and maintenance. Recovering the

resources from the waste also significantly lowered the global warming potential of these

systems from 2,079-49,655 kgCO2 eq to 616-1,882 kgCO2 eq; significantly less than the global

warming potential of VIP latrine or pour-flush latrines (8,642-15,789 kgCO2 eq). In addition, two

community wastewater treatment systems that serve 420-1,039 individuals considered in a

similar study had a higher cumulative energy demand per household (44,869 MJ and 38,403

MJ) than the household sanitation systems (11,275-19,990 MJ). The community wastewater

vii

treatment systems had a lower global warming potential (2019-2,092 kgCO2 eq) than household

systems that did not recover resources (8,642-15,789 kg CO2 eq), but higher than household

systems that incorporate resource recovery (616-1,882 kgCO2 eq). The goal of this study is to

provide insight to policy makers in the development field to promote decision making based on

environmental sustainability in the implementation of improved sanitation coverage in rural

areas of developing countries.

1

CHAPTER 1: INTRODUCTION

1.1 Research Motivation

2.5 billion people currently lack access to basic sanitation worldwide (WHO/UNICEF,

2012). The United Nations (UN) Millennium Development Goal (MDG) 7 Target 3 seeks to halve

this number of people not served by improved sanitation by 2015 while ensuring environmental

sustainability (UN, 2006). Although significant progress has been made, the world is likely to fall

short of this goal. In addition, increasing greenhouse gas (GHG) concentrations and projected

anthropogenic climate change appear likely to negatively impact sustainable development

(IPCC, 2007). Water use is a major component of environmental sustainability and 70% of the

world’s fresh water is already used for irrigation (Zimmerman et al., 2008). Furthermore,

agricultural production, water, and energy use will continue to increase as the global population

approaches an expected 9 billion people in 2050 (FAO, 2011). Health and economic factors are

commonly used to evaluate sanitation systems; however, this study provides an environmental

sustainability context that, as part of a holistic approach, can be used when considering the

improvement of sanitation coverage in developing countries and around the world. This is part

of a new paradigm that has emerged in wastewater treatment where the sanitation systems are

now viewed as resource recovery systems (RSSs), that should allow the perceived negative

impact of wastewater to become a net positive impact (Guest et al., 2009).

The relationship between sanitation, water quality, and health has long been recognized

as a valuable topic for academic research, professional journals, and international funding (e.g.,

Clasen and Bastable, 2003; Clasen et al., 2007; Fry et al., 2010; CDC, 2012). For example, the

World Health Organization (WHO) estimates that consumption of contaminated water and lack

of sanitation and hygiene account for 3.2% of deaths and 4.2% of Disability Adjusted Life Years

2

(DALYs) associated with diarrheal diseases worldwide (WHO, 2009). Table 1 provides mortality

and the percent of DALYs attributable to diarrheal disease globally and regionally. This table

shows there are an estimated 4 billion cases of diarrheal disease worldwide per year (Kosek et

al., 2003), resulting in 2 million deaths (WHO, 2008). In addition, diarrhea accounts for 17% of

all deaths in children under the age of 5 in developing countries (UN, 2006).

The Center for Disease Control (CDC) (2012) states that access to safe water and

sanitation facilities (e.g. latrines), as well as knowledge of proper hygiene practices, can reduce

the risk of illness and death from waterborne diseases, leading to improved health, poverty

reduction, and socio-economic development. Despite recent gains in both rural and urban areas

in developing countries, rural areas still lag behind significantly in terms of access to an

improved water source and sanitation. As seen in Figure 1, in 2010 65% of the rural Peruvian

population had access to an improved water source and 37% had access to improved

sanitation. The modest gains in each indicator from 1990 to 2010 coincide with reduction of the

under-5 mortality rate in Peru from 75 to 19.4 deaths per 1,000 births (World Bank, 2013). While

this does not signify a direct correlation, many studies have suggested that a correlation does

Table 1: Burden of diarrheal disease by global region, 2000. Source: Nath et al. (2006)

Deaths and DALY Totals for 2000

Global Africa Americ

as

Southe

ast Asia Europe

East

Mediter

ranean

West

Pacific

% Mortality

due to

Diarrheal

Disease

3.2% 6.6% 0.9% 4.1% 0.2% 6.2% 1.2%

% DALYs

due to

Diarrheal

Disease

4.2% 6.4% 1.6% 4.8% 0.5% 6.2% 2.5%

3

exist between improved water and sanitation services and under-5 mortality rates (Sobsey et

al., 2003).

The primary function of sanitation systems is to protect human health by containing

and/or treating human waste and its associated pathogen content. However, the effect of these

systems on human health is not considered in this study, rather the environmental sustainability

Figure 1: Access to water and sanitation statistics and child mortality rates for Peru. (a)

Percent of Peruvian population with access to improved sanitation.(b) Percent of Peruvian

population with access to improved water source. (c) Under-five mortality rate per 1,000 births

for Peru. Source: World Bank (2013).

0

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4

of household sanitation systems is analyzed in terms of the amount of embodied energy and

greenhouse gas (GHG) emissions associated with particular sanitation technologies, some

which include resource recovery as a design objective.

1.2 Objective and Hypotheses

In this study, a Life Cycle Assessment (LCA) is performed on four household sanitation

systems found in the region of Alto-Piura, Peru. Some of the sanitation technologies evaluated

in this study are integrated with resource recovery. The sanitation systems are assessed and

compared quantitatively for their environmental sustainability in terms of embodied energy (MJ)

and carbon footprint (kgCO2 eq). Although these household systems have a relatively small

environmental impact individually when compared to other wastewater treatment systems,

especially in developed countries, when extrapolated over the 2.5 billion people who currently

lack access to improved sanitation worldwide (WHO/UNICEF 2012), their implementation may

be significant on a regional or global scale. This study also compares the results of the

environmental sustainability of household sanitation systems to the results from a study

performed in rural Bolivia on small community-managed sanitation systems designed to serve

between 700 and 1,500 people employing wastewater lagoons and anaerobic reactors. This

provides an evaluation of the influence that scale of the sanitation technology will have on the

environmental sustainability of sanitation coverage in developing countries. Accordingly, two

hypotheses were developed for this research.

1. Although they will have higher Cumulative Energy Demand (CED) due to increased

material requirements during installation and maintenance, sanitation systems such as

composting latrines and biodigester latrines that incorporate energy recovery will have

lower Global Warming Potential (GWP) over their service life when compared to

ventilated improved pit (VIP) latrines and pour-flush latrines.

5

2. Because of the high amount of energy associated with installation and maintenance of

community waste collection systems, it is expected that decentralized household level

collection and treatment systems will have comparatively lower CED per household than

a centralized waste collection system.

6

CHAPTER 2: PREVIOUS RESEARCH AND BACKGROUND INFORMATION

2.1 Nutrient Content of Human Excreta

Resource and energy recovery can play an important role in helping to reduce the

energy, costs, and resources of wastewater treatment. Table 2 provides the basic

characteristics of human excreta. This table shows that the average person produces 500 kg of

urine and 50 kg of feces per year, containing 5.7 kg of nitrogen, 0.6 kg of phosphorus, and 1.2

kg of potassium (Heinonen-Tanski and van Wijk-Sijbesma, 2005). Recycling all the nutrients in

domestic wastewater could reduce the global use of commercial fertilizers by 35-45% (Lind et

al., 2001). One study quantified the amount of phosphorus produced in human excreta (urine

and feces) worldwide as being 1.6 million metric tons in 2009, which corresponds to

approximately 22% the global phosphorus demand (Mihelcic et al., 2011). In addition, Verbyla et

al. (2013) estimate that the effluent of two community wastewater treatment plants in Bolivia

contain the same amount of nutrients as the fertilizer used to produce crops containing 10-75

days’ worth of the recommended food energy intake for each person discharging waste to the

system. Recovery of the nutrients found in human waste thus has a great potential as a more

sustainable strategy to offset commercial fertilizer needs.

Table 2: Characteristics of daily human excreta per person. Adapted from Esrey (2000).

Elements Urine

(grams/capita-day)

Feces

(grams/capita-day)

Urine + Feces

(grams/capita-day)

Nitrogen 11.0 1.55 12.5

Phosphorus 1.0 0.5 1.5

Potassium 2.5 1.0 3.5

Organic Carbon 6.6 21.4 30

Wet weight 1,200 70-140 1,200-1,400

Dry weight 60 35 95

7

2.2 Anaerobic Digestion

One common wastewater treatment strategy for energy and resource recovery in tropical

and sub-tropical climates is the anaerobic digestion of wasted solids from the activated sludge

treatment process. This strategy provides two benefits: (1) biogas is generated, which can be

combusted to produce heat and electricity and (2) fertilizer can be processed from the biosolids,

and is often marketed as a substitute to commercial fertilizers. For example, the 54.2 million

gallon per day Howard F. Curren, advanced wastewater treatment plant (WWTP) in Tampa, FL,

uses biogas powered generators to produce 36,000 kWh of energy per day, approximately 25%

of the plant’s energy use. Additionally, 22.2 dry tons of processed sludge are harvested per day

for land application (City of Tampa, 2012). Anaerobic processing of industrial waste and

municipal wastewater is not limited to the U.S. and it is also common in countries such as Brazil,

China, India, Colombia and Mexico, as a way to improve sanitation infrastructure and recover

valuable resources. For instance, 85 Upflow Anaerobic Sludge Blanket (UASB) wastewater

treatment plants were constructed in Mexico between 1987 and 1998 (Monroy et al., 2000).

Energy and resource recovery through anaerobic digestion is also possible at the

household level. Numerous studies have examined household biodigestion as a means of

management of human and agricultural wastes in developing countries due to their potential for

energy and resource recovery (Gunnerson and Stuckey, 1983; GTZ, 1999; Buysman, 2009;

Walekhwa et al., 2009; Ocwieja, 2010; Rowse, 2011). For example, Chen et al. (2010) report

that as of 2007, 26.5 million household biodigesters using pig, human, and agricultural waste

feed have been built in China. From 1991 to 2005 an estimated 833,000 TJ of energy was

produced by these systems in China, resulting in a reduction of greenhouse gases (GHG)

emissions of 73,200 Gg CO2 equivalents (Yu et al., 2008).Another study found that users in the

Liangshui and Guichi counties of China used 2,175 kWh (7,831 MJ) per year from biogas per

household (Xiaohua et al., 2007).

8

Resource recovery from the biodigester is also associated with the use of the nutrient

rich effluent as fertilizer. Nutrient concentrations in the effluent vary widely depending on influent

concentrations and management practices, such as collection method, flush water, bedding,

and dilution rate. Table 3 provides values found in literature of nutrient concentrations of

potential biodigester feed materials. Although nitrogen does undergo a chemical transformation

from the organic form to a mineral form, in general, plant nutrients such as nitrogen,

phosphorus, and potassium are conserved during anaerobic digestion. The reduction in total

Kjeldahl nitrogen as a result of anaerobic digestion reported in several studies is likely due to

the fact that only the supernatant is analyzed for nitrogen content of the effluent and solids

contain 34.5% of the total nitrogen of the effluent (Massé et al., 2007).

Several studies have also investigated the effectiveness of biodigestion with respect to

the elimination of pathogens commonly found in wastewater. Although many bacteria can

survive prolonged periods in an anaerobic environment, small scale biodigesters have been

found to effectively remove pathogens, such as Salmonella Typhi and Escheria Coli, based on

the operating temperature and retention time (Côté et al., 2006). Temperature is an important

Table 3: Nutrient concentrations of potential biodigester feeds.

Nitrogen

(mg N/L)

Phosphorus

(mg P/L)

Potassium

(mg/L) Source

Fresh cow

manure

12,000 1,700 1,100 (FAO, 2005)

5,730 1,140 3,130 (USDA, 2008)

6,620 1,150 1,520 (ASAE, 2005)

Poultry 22,000 18,000 11,000 (FAO, 2005)

18,100 5,700 6,730 (USDA, 2008)

Swine 7,080 2,080 4,420 (ASAE, 2005)

7,440 2,150 4,700 (USDA, 2008)

Human Feces 7,000 2,330 4,670 (Esrey, 2000)

9

operational parameter in terms of how pathogens are destroyed during anaerobic digestion. For

example, destruction times of pathogens are generally represented in months in the

psychrophilic range (-10 to 15°C), days in the mesophilic range (20 to 45°C), and hours in the

thermophilic range (45 to 120°C) (Sahlström, 2003). Residence time of the waste is also

important. For example, Taiwanese-style biodigesters typically operate with a 45-day solids

retention time in the mesophilic range (Gunnerson and Stuckey, 1986). In addition, a laboratory

experiment of batch anaerobic digestion found that all Salmonella was removed after 15 days at

35°C or after 25 days at room temperature and 99.6% of E. coli was removed in 5 days at 35°C

(Kumar et al., 1999). Another field study measured zero coliform forming units (CFU) in the

effluent of a Taiwanese style biodigester operated with a 50-day solids retention time (Botero

and Preston, 1987).

Furthermore, Massé et al. (2011) found that although the majority of pathogens found in

swine waste (e.g. Salmonella, Campylobacter spp., and Yersinia enterocolitica) were reduced

below detectable levels when treated by psychrophilic sequenced batch reactors; however,

Clostridium perfringens and Enterococcus spp levels remained high within the digesters

throughout treatment. Although research shows the substantial removal of pathogens from

waste through anaerobic digestion, proper waste management should be used to reduce the

risk associated with use of effluent in agriculture, especially when human waste is digested.

2.3 Pathogen Destruction in Composting Latrines

Composting latrines have been promoted by development organizations as a sanitation

technology with the added benefit of resource recovery through organic fertilizer production.

However, social acceptability of this technology varies in different parts of world. For example, in

China and Southeast Asia the use of human excreta as agricultural fertilizer has been common

for thousands of years. One study found that 75% of farmers surveyed in central Vietnam

reported using fresh or partially composted human feces to fertilize their farmland or garden

10

(Jensen et al., 2013). In contrast, acceptability of composting latrines in other parts of the world

such as Africa and Central and South America may be lower and depend strongly on the

education and training aspects of individual projects (Karlsson and Larsson, 2000; Hurtado,

2005).

Elimination of pathogens in feces is dependent upon a few important environmental

factors in the latrine: temperature, time, pH, and moisture content. Figure 2 provides the time

and temperature required to destroy certain pathogens. Heat is a by-product of aerobic

decomposition and Vinneras et al. (2003) found that an insulated composting latrine can reach

temperatures above 60°C and successfully eliminate pathogens. Hurtado (2005) and Kaiser

(2006) warn that composting latrines in the field may operate at ambient temperatures, but still

may effectively remove pathogens due to elevated pH (Kaiser, 2006). Furthermore, a field study

and laboratory analysis of 63 composting latrines in Panama found latrines operating at an

average temperature of 29.5°C, compared to 29°C average ambient temperature. These

latrines did not sufficiently eliminate pathogens when operated with a six month storage times;

therefore, a one year storage period was recommended instead (Mehl et al., 2011). Table 4

provides the results of the microbiological analysis of five compost samples from the study by

Mehl et al. (2011). Pathogens, such as Ascaris lumbricoides which is commonly used as an

organism of concern in pathogen removal studies, were present in many of the samples.

11

Figure 2: The influence of time and temperature on a variety of excreted pathogens. The

lines drawn represent conservative upper boundaries for death. Source: Cairncross and

Feachem (1993) with permission.

12

Several studies have determined that in order to improved aerobic decomposition in a

composting latrine, the addition of desiccant after each use is necessary to not only desiccate

pathogens, but also raise the carbon to nitrogen (C:N) ratio to the ideal ratio of 15:1 to 30:1

(Karlsson and Larsson, 2000; Mehl et al., 2011). The C:N ratio of wood ash and saw dust,

commonly used desiccants, are 25:1 and 200-500:1, respectively. Untreated human feces have

approximately a 5:1 C:N ratio, while finished compost has a 10:1 C:N ratio (Richard and

Trautmann, 1996). Often insufficient desiccant is added by the users to raise the ratio to the

recommended value as seen in Table 5. The additional nutrients found in compost increased

the yield of covo, spinach, lettuce and onions by 300-700% in field trials in Mozambique using

composted human feces in a 50:50 mixture with regular soil (Morgan, 2007).

Table 4: Microbiological analysis of five samples obtained from active compost latrines in

Panama. (N/O = Not Observed) Data from Mehl et al. (2011).

Bacteria Helminths Protozoa

Samp

le

Total

colifor

ms

(CFU/

100

g)

E. coli Salm

onella

Shigu

ella

Klebsi

ella

(CFU/

100

g)

Taeni

asoliu

m

Taeni

asagi

nata

Ascari

slumb

ricoid

es

Trichu

ristric

hura

Enta

moeb

as

Giardi

a

lambli

a

A 8.E+0

4 N/O N/O N/O N/O N/O N/O

infertil

e egg

infecti

ve

egg

Enta

moeb

a coli

cyst

N/O

B 7.E+0

3 N/O N/O N/O N/O eggs N/O

infertil

e egg N/O N/O N/O

C 3.E+0

4 N/O N/O N/O

4.E+0

3

adult

sectio

ns

and

eggs

N/O egg N/O N/O N/O

D 3.E+0

4 N/O N/O N/O

6.E+0

3 N/O N/O

fertile

egg N/O N/O N/O

E 7.E+0

4 N/O N/O N/O N/O N/O N/O

infertil

e egg N/O N/O N/O

13

2.4 Life Cycle Assessments Related to Water and Wastewater

Life cycle assessment (LCA) is a tool for quantitatively analyzing processes or products

for their environmental impact, including the life stages of raw material extraction, transport,

construction, use, and end-of-life phases (EPA, 2006). An important engineering process now

being analyzed with LCA is the treatment and distribution of water, which accounts for 2-3% of

the world’s total energy demand (James et al., 2002) and 3% in the U.S. (EPA, 2008b).The goal

of applying the LCA method to wastewater treatment technology is to quantify energy and

resource consumption within the process and identify opportunities to improve the overall

environmental sustainability.

Cumulative energy demand in megajoules (MJ) and carbon footprint in kilograms of

greenhouse gas equivalent (kgCO2 eq) are commonly used to quantify the results of an LCA

and allow for comparison with other studies. However, the majority of current studies have

focused on large scale facilities in developed countries (100+ MGD wastewater treatment

plants) and there is little research available on smaller systems in developing countries. For

example, Mo and Zhang (2012) analyzed the potential benefits of integrated resource recovery

of energy, nutrients, and water at the 54.2 MGD Howard F. Curren advanced WWTP in Tampa,

FL. It was found that on-site energy generation from biogas, land application of digested sludge,

and water reuse for residential irrigation together could offset all direct operational energy of the

plant (accounting for 90% of its total embodied energy and carbon footprint of the plant), but not

Table 5: Chemical composition of compost samples. Adapted from Mehl et al. (2011).

Sample pH

Moisture

content

(%)

C (%) N (%) C:N P (%) K (%)

A 9.18 36.7 2.03 0.35 5.8 0.24 2.79

B 9.45 29.5 1.93 0.36 5.4 0.24 3.62

C 9.48 66.8 19.85 2.34 8.5 0.46 3.13

D 6.46 49.6 12.92 1.41 9.2 0.41 1.58

E 8.45 46.7 6.19 0.89 7 0.41 3.06

14

the total embodied energy of the plant (which includes the construction phase). Another study

compared direct, indirect, and total embodied energy of two drinking water treatment plants in

the U.S., one in Tampa, FL using surface water as its source and the other in Kalamazoo, MI

using groundwater as a source. It found that the two plants had comparable total embodied

energy per volume of water provided (10.3 MJ/m3 for the groundwater plant and 10.7 MJ/m3 for

the surface water plant). However, the groundwater plant had higher direct energy usage due to

increased pumping requirements while the surface water plant had higher indirect energy usage

due to the additional treatment and chemicals required for the lower quality raw water source

(Mo et al., 2011).

A study in rural Bolivia compared the cumulative energy demand and GHG emissions

over a 20-year period of two community wastewater treatment systems serving between 420-

1,039 users with different water reuse and energy recovery conditions. It was determined that

for an existing Upflow Anaerobic Sludge Blanket (UASB) reactor, the addition of energy

recovery from biogas would reduce the carbon footprint by 57.2% compared to the existing

condition. In comparison, reuse of effluent for a three-pond wastewater treatment system would

reduce the carbon footprint by 0.1-2.1% compared to river water irrigation (Cornejo et al., 2013).

In another study investigating the economic, social, and environmental sustainability of

community wastewater treatment facilities, basic treatment methods, such as lagoons, were

determined to be more appropriate than mechanical treatment methods, such as activated

sludge (Muga and Mihelcic, 2008). In many rural areas, community systems that include a

collection system and treatment lagoons are not feasible due to cost, community size, low

population density, geography, lack of funding for infrastructure, and/or inability to operate and

maintain the facility (IPCC, 2007). In this case, household level systems may be more

appropriate. In order to meet the United Nations MDG 7 target for improved sanitation coverage

many more household sanitation systems will need to be constructed. When considered on a

15

global scale, this represents a large investment of finite resources, especially for local or

regional governments of developing countries.

One study was identified that analyzed the embodied energy of eight water supply

interventions in Sub-Saharan Africa (four source level and four household level) (Held et al.

2012). Table 6 provides the embodied energy of these interventions. Human energy was

included in the calculation of the embodied energy and, although it is typically considered

negligible in this type of analysis, accounted for over 90% of the total embodied energy in four of

the eight interventions. When the human energy is segregated by gender it shows that over

99% is provided by women (mainly during the use phase) and 1% by men (mainly during the

construction phase) for seven of the eight interventions.

2.5 Sanitation Technologies Evaluated in this Study

2.5.1 Ventilated Improved Pit Latrine

The Ventilated Improved Pit (VIP) latrine is a relatively basic sanitation technology

common in rural areas of developing countries due to its low cost and ease of maintenance.

Similar to the standard pit latrine, it consists of three parts: (1) the pit, (2) the platform, and (3)

the superstructure (see Figure 3). Materials used to construct the privacy structure can vary,

depending on local preferences and availability; however, adobe brick, clay brick, or corrugated

metal are common. The VIP latrine should be oriented so the prevailing wind enters the pit

Table 6: Embodied energy of eight water supply interventions in Mali. Adapted from Held et al.

(2012).

Intervention Intervention type Embodied Energy (GJ per

functional unit)

Rope pump Source protection 117

Chlorination Point of use 131

Improved well Source protection 134

Biosand filter Point of use 139

India Mark II hand pump Source protection 245

Solar pump Source protection 302

Ceramic filter Point of use 343

Boiling with fuelwood Point of use 172,559

16

through the superstructure and exits through the ventilation tube, suppressing unpleasant odors

inside. Additionally, the ventilation tube is placed where it will be heated by sunlight to promote

the upward flow of air out of the pit. The pit may be lined or unlined, depending on soil type. The

service life can be estimated with the following formula:

�� = �� ∗ ��ℎ

�� ∗ ��

The accumulation rate is typically 0.2-0.9 m3/capita-year depending on the pit’s contact

with the water table and the anal cleansing materials used (Mihelcic et al., 2009). When the pit

is around 80% full (typically around 30 cm from the slab) a new pit should be dug and the latrine

relocated, reusing the materials in the privacy structure if possible. The original pit should be

capped with soil to prevent contamination of the surrounding area and is an ideal location for

planting a fruit tree to take advantage of the nutrients of the waste left in the pit.

17

2.5.2 Composting Latrine

The composting latrine is a household sanitation option that converts human excrement

to a soil amendment which improves the physical structure and nutrient content of soil. Because

the latrine is constructed above ground and sealed, it can be built in areas with high ground

water tables or close to surface water sources without risk from seasonal flooding. A double

vault latrine is usually constructed as shown in Figure 4. The vaults are used alternately-- so

while one is in use, the waste in the other is being composted. The urine diversion style (as

seen on the right of Figure 4) has a separator seat which transports the urine outside of the

Figure 3: Components of a VIP latrine. Source: Figure from Mihelcic et al. (2009) with

permission provided by Linda A. Phillips.

18

latrine where it may be collected (as considered in this study) or can be allowed to drain into a

soak pit. Diverting the urine promotes the decomposition of the feces in two ways: (1) by

lowering its moisture content and increasing oxygen transfer within the compost and (2) by

raising the C:N ratio of the compost by isolating the nitrogen found in urine from the composting

feces. The urine is also easily reused as fertilizer (Shaw, 2010). Composting latrines require

specific use and maintenance to ensure their proper functioning. For example, a dry organic

desiccant must be kept on hand for addition after each use and the compost removed when it is

ready for harvesting (i.e., annually).

2.5.3 Pour-Flush Latrine

The pour-flush latrine uses water to flush solids from the bowl to a collection pit. It is

popular in many developing countries because it resembles the indoor system found in sewered

communities commonly seen in urban areas. The design is typically covered with a reinforced

concrete slab and can incorporate a squatting or traditional style seat. The bowl has water seal

trap (see Figure 5) that prevents flies from entering the pit and odors from passing into the

latrine. The pit is lined but not sealed (i.e., spaces are left between the bricks) allowing the

liquids to permeate to the surrounding soil while retaining the solids. Outside of this lining there

is 10 cm of gravel which filters the liquid and helps to ensure proper drainage to the soil.

Figure 4: Two-vault composting latrine. Source: Figure from Mihelcic et al. (2009) with

permission provided by Linda A. Phillips.

19

Overall, pour-flush latrines are appropriate in areas with reliable, year-round water supply that

can accommodate the extra water usage associated with flushing the latrine.

2.5.4 Biodigester Latrine

Figure 6 provides a diagram of a household biodigester latrine using a Taiwanese

flexible bag-style digester. Figure 7 provides a photo of what this type of biodigester looks like in

the field. This system is operated semi-continuously with inputs from both the household flush

latrine and manually mixed slurry from cow manure. A solids retention time of 45 days is

recommended to allow time for proper functioning of the reactor. As the reactor is filled the

entrance and exit pipes are sealed by the contained slurry, preventing air from entering the

reactor and allowing the anaerobic digestion process to take place. This initial loading of the

reactor is referred to as “charging” the digester and consists of a period of 2-3 weeks of

operation while the anaerobic bacteria and archaea involved in methanogenesis (production of

methane) multiply and produce biogas. The reactor and reservoir are made from a

Figure 5: Pour-flush latrine with off-set collection pit. Source: Figure from Mihelcic et al. (2009)

with permission provided by Linda A. Phillips.

20

geomembrane PVC and inflate to a sufficient pressure for the household use of biogas for

cooking, lighting, or heating. In addition to the production of biogas, the biodigester produces a

nutrient rich effluent which can be used as an agricultural fertilizer.

Figure 6: Diagram of Taiwanese style household biodigester latrine.

21

Figure 7: Photo of Taiwanese biodigester installed in Santo Domingo, Piura, Peru (photo from

Christopher Galvin).

22

CHAPTER 3: METHODS 3.1 Goal and Scope Definition

The goal of this study is to quantitatively estimate and compare the environmental

sustainability of four sanitation systems found in the Alto-Piura region of northern Peru, and

common in rural areas of other developing countries. While each represents a relatively small

use of resources or investment during construction and use phases, when extended over a

regional, national, or global scale the results are significant. This study is intended to provide

insight to policy makers in the development field interested in environmental sustainability and

to provide reliable data related to local materials, culturally appropriate technology, energy and

resource recovery, and water conservation.

3.2 Site Location

This study takes place in the department of Piura (Peru). As shown in Figure 8, the

department of Piura is located in northern Peru on the western side of the Andes Mountains

sharing a border with Ecuador.

23

Piura has a population of 1.6 million and is divided into 8 provinces and 64 districts and

has an area of 35,893 km2. Spanish is spoken exclusively in the area. The capital of the region

is Piura which is the most populated city.

This study is based in the district of Santo Domingo in the region of Alto-Piura, 130 km

east of the department capital. It has an area of 187.3 km2 and a population of approximately

8,000. It is a highly rural district with 87% of the district population dispersed between 41

communities of 200 people or less, many of which are without road access or basic sanitation

services. The district population has declined 14% since 1993, primarily due to emigration

(Municipality of Santo Domingo, 2008).

Figure 8: Location of study site in Piura, Peru.

24

Various strategies and latrine designs have been implemented in Santo Domingo by the

national government, local municipality, and international NGOs. Four types of latrines have

been chosen for life cycle assessment in this study: (1) Ventilated Improved Pit (VIP) latrine, (2)

pour-flush latrine, (3) composting latrine, (4) biodigester latrine. All four are sanitation systems

designed to protect human health while the third and fourth also incorporate energy/resource

recovery options. Table 7 provides the basic characteristics of the four latrines considered in

this study.

3.3 Defining the Functional Unit and System Boundary

The functional unit for this study is based on the primary function of the sanitation

systems which is the containment and treatment of human waste (urine and feces) produced by

one household-equivalent over a 20-year period. Demographic data reports an average of 5.05

people per household in the study location (Municipality of Santo Domingo, 2008). The

treatment of cow manure that is added to the biodigester is a secondary function of this system,

and therefore the cow manure is considered an additional input to the system apart from the

functional unit.

Table 7: Basic characteristics of the four latrine technologies considered in this study.

VIP Latrine Pour-Flush

Latrine

Composting

Latrine

Biodigester

Latrine

Estimated cost

(USD) (20 years) 135.34 893.20 495.38 2065.79

Operational

Maintenance Minimal Medium High High

Expected life 10 years 10 years 20 years 7 years

Water use None 1-5 L per flush None 1-5 L per flush

Mechanism to

protect human

health

Containment Containment

Containment

and Pathogen

Destruction

Containment

and Pathogen

Destruction

Resource

recovery No No

Yes, compost

and urine

diversion

Yes, biogas

and effluent

25

A flowchart of the inputs and outputs for the use phase of each sanitation system is

provided in Figure 9. The VIP latrine and pour-flush latrine systems are relatively less complex

with the human waste being degraded to carbon dioxide and methane emissions to air. The

composting latrine and biodigester latrine outputs vary slightly depending on the operation. For

example, the composting latrine may or may not be used to recover the nutrients (nitrogen, in

this case) in feces and urine. In the case of the biodigester latrine, its operation affects the

biogenic emissions produced. Theoretically, the biogas is combusted and no methane is

released; however, the escape of a certain portion of biogas is unavoidable (i.e., from the inlet

and outlet), especially if the system is operated improperly (i.e., operated with a leak in the gas

system) or the biogas is not regularly used, methane may be directly emitted to air.

26

Figure 9: System diagram showing the inputs and outputs for: (a) VIP latrine (b) pour-flush

latrine (c) composting latrine and (d) biodigester latrine.

27

3.3.1 Data Collection and Life Cycle Inventory

Figure 10 provides the LCA framework for materials associated with the four sanitation

technologies. The designs and project budgets for the VIP and composting latrine were

provided by Peace Corps Peru through its technical library. The pour-flush latrine is currently

being implemented by the municipality of Santo Domingo and its design was provided by civil

engineer Cesar Castillo. Several Taiwanese style biodigesters have been installed in the study

site; however, the biodigester latrine is based on literature on biodigesters used as household

sanitation systems (Gunnerson and Stuckey, 1986; GTZ, 1999; Ocwieja, 2010) and developed

in discussions between civil engineer Cesar Castillo and the author. Table 8 provides the model

inputs, data sources, and inventory items used in the LCA in this study.

Material inventories were compiled for each system and entered in SimaPro 7.2 (PRé

Consultants, 2008) using the Ecoinvent database (St. Gallen, Switzerland). Materials and

processes used from the database, such as transport, were assumed to be the same for the

study location.

28

Figure 10: LCA framework used in this study for materials associated with the four household

sanitation technologies.

29

3.4 Calculations for Life Cycle Inventory

3.4.1 Material Production

The total material mass that makes up a particular sanitation technology was estimated

as follows:

�� = ∑ �� ! ∗ ��ℎ� ��"��#!$!%& (1)

where mass is the weight (kg) of a particular material. The majority of the materials have a

purchase frequency of one, because they do not need to be replaced over the 20-year system

Table 8: Model input data collected and SimaPro inputs (adapted from Stokes and Horvath,

2006)

Model Inputs Data Sources Inventory Items

Material Production:

Material Type, Material

Properties (kg or m3),

Service Life (years),

Purchase Frequency

(qty)

Source: Project documents: Budget

VIP Latrines, Budget Composting

Latrines, Budget Biodigester (Peace

Corps Peru Technical Library); Cesar

Castillo (Civil Engineer, Municipality of

Santo Domingo)

Contribution: Material production data

Mass (kg) or

volume (m3) of

materials used

over 20-year

lifespan

Material Delivery:

Material Origin (City),

Distance (km), Cargo

Weight (kg), Mode of

Transportation (vehicle

type)

Source: Project documents: Budget

VIP Latrines, Budget Composting

Latrines, Budget Biodigester (Peace

Corps Peru Technical Library); Cesar

Castillo (Civil Engineer, Municipality of

Santo Domingo)

Contribution: Material delivery data

Freight

transportation

quantity (kg-km)

of materials

delivered to site

over 20-year

lifespan

Resource Recovery:

Volume (m3) of natural

gas avoided, Mass (kg)

of fertilizer use avoided

Source: EPA (2010); Rittmann and

McCarty (2001); ASAE (2005);

Jönsson et al. (2004); Esrey (2000)

Contribution: Production and energy

content of biogas (m3) by biodigester,

nitrogen concentration in cow manure

and human urine and feces

Volume (m3) of

natural gas

avoided over 20-

year lifespan,

Mass of N (kg) of

fertilizer use

avoided over 20-

year lifespan

Biogenic Emissions:

Mass (kg) of carbon

dioxide and methane

Source: EPA (2010)

Contribution: Production of biogenic

emissions by each system

Mass (kg) of

carbon dioxide

and methane

over 20-year

period

30

life. The geomembrane reactor and gas reservoir for the biodigester latrine were assumed to

have a 7-year life (2.68 purchase frequency). The service lives of the VIP and pour-flush latrines

are based on the amount of time for the pit to fill with accumulated solids, which was assumed

to be 10 years. Therefore, the entire VIP latrine (superstructure and pit) must be reconstructed

only once over the 20-year period and the materials associated with the construction have a

purchase frequency of 2. In the case of the pour-flush latrine, the superstructure and plumbing

are still serviceable if connected to a new pit; therefore, it is only necessary to construct a new

collection pit once over a 20-year period. Thus the materials associated with the construction of

a new collection pit (brick, cement, sand, gravel, and rebar) have a frequency of 2.

3.4.2 Material Delivery

Material delivery was determined in kg-kilometers (kg-km) for each system as follows:

'��#��-�� = ∑ �� !�� ∗ '� ��!��$!%& (2)

In Equation 2, mass is the weight (kg) of a particular material and distance is the

distance the material is transported to the construction site. Some materials are available

locally, such as water and wood, while others are produced in other locations and transported to

the site location by truck. The truck capacity was assumed to be 3-16 tons based on the

author’s in country experience. Specific distances from material origin to the study location are

provided in Table 9.

31

3.4.3 Biochemical Oxygen Demand Input

As can be seen previously in Figure 9, each system has the input of urine and feces

from humans that occupy one household, while the input to the biodigester is augmented with

cow manure slurry. A value of 80 g BOD/capita-day (Metcalf & Eddy, 2003) was used to

calculate the organic loading per household in the following calculation:

80*+,-

./0!1/∗2/3∗ 5.05

067086

97:;69782∗&<*

&=>*∗ ?@A2/3;

&36/B∗ 20#�� = 2,950

<*+,-

97:;69782 (3)

Values for latrine flush volume and frequency were obtained from Mihelcic et al. (2009)

and were used to determine water use for the pour-flush and biodigester latrine:

2.5F

G8:;9∗ 5

G8:;9

2/3∗06B;7$∗ 5.05

067086

97:;69782= 63.1

F

97:;69782∗2/3 (4)

A 10-m3 biodigester with a 45-day solids retention time would have a flow rate of 222

L/day. 63.1 L/day are supplied by the latrine; therefore, 159 L of slurry (1:3 mixture of manure to

water) should be added per day. Based on the value of 22.2 kg BOD/m3 for fresh manure

(USDA, 2008) the total BOD content of the slurry for the 20-year period was determined as

follows:

22.2<*+,-

K>K/$:B6∗&K>K/$:B6

LK>;8:BB3∗ 159

F;8:BB3

2/3∗&K>

&=>F∗?@A2/3;

&36/B∗ 20# = 6440��NO' (5)

Table 9: Distances to site location from material origins.

Distance (km) to site location

Santo Domingo, Piura, Peru Material

Local 0 water, wood

Morropon 45.5 sand, gravel

Buenos Aires 63.1 clay brick

Piura 130 PVC tubes and

accessories

Pacasmayo 449 cement

Lima 1108

PVC geomembrane

biodigester reactor and

reservoir, rebar,

corrugated metal

32

Therefore the total BOD input to the biodigester over 20 years was estimated to be

9,390 kg.

3.4.4 Anaerobic Degradation of Domestic Wastewater

The biochemical oxidation of the organic constituents found in wastewater through an

anaerobic treatment process can be described by the following stoichiometic equation derived

from Rittmann and McCarty (2001):

�&=P&QO?� + 5.01PSO → 5.94�PL + 2.57�OS + 0.23�APVOS� + 0.89�PLW + 0.89P�O?

X (6)

In Equation 6, domestic wastewater is assumed to be the electron donor and carbon

dioxide the electron acceptor and the stoichiometric molar requirements of methane, carbon

dioxide, and biomass per mole of BOD are also provided. The growth rate of the

microorganisms in the anaerobic process is typically much lower than aerobic processes and

methane makes up 60-70% of the biogas produced, while carbon dioxide makes up the other

30-40% with trace amounts of N2, H2, and H2S (Rittmann and McCarty, 2001). As mentioned

previously, this process is commonly used in wastewater treatment and is considered in this

thesis in the calculation of biogenic emissions and biogas production.

3.4.5 Aerobic Degradation of Domestic Wastewater

In the presence of oxygen, the biochemical oxidation of domestic wastewater can be

described by the following stoichiometric equation derived from Metcalf and Eddy (2003):

�&=P&QO?� + 4.5OS + 0.6�PLW + 0.6P�O?

X → 1.6�APVOS� + 5.4PSO + 2.6�OS(7)

This reaction is commonly used to describe the treatment of organic matter found in

municipal wastewater through the activated sludge process. The biomass is supplied with

oxygen and grows in the aeration basin while converting organic carbon to CO2. Typically the

secondary clarifier settles and recycles the majority of the biomass back to the aeration basin.

33

The reaction may also be applied to the degradation of waste in other systems, such as the

upper region of a facultative lagoon or, as considered in this study, a composting latrine.

3.4.6 Biogenic Emissions

In general, biogenic emissions to air are associated with the decomposition of feces in

both aerobic and anaerobic environments. Equations 6 and 7 provide the theoretical basis for

the production of methane and carbon dioxide. For the purpose of comparing the results with

those of Cornejo et al. (2013) the following method for calculating the biogenic air emissions

obtained from the EPA (2010) was used to calculate the methane and carbon dioxide values:

�OS = NO' ∗ Y,- ∗ �Z[,S ∗ [�1–��Z ^ ∗ N_[`L��1 − b�] (8)

�PL = NO' ∗ Y,- ∗ �Z[`L ∗ [��Z ^ ∗ N_[`L��1 − b�] (9)

In Equations 8 and 9:

CO2 = CO2 emissions (kg) over 20 years

CH4 = CH4 emissions (kg) over 20 years

BOD = Biochemical Oxygen Demand of influent (kg) over 20 years

EffOD = Oxygen demand removal efficiency, assumed 80%

CFCO2 = Conversion factor for maximum CO2 generation per unit of BOD

= 1.375 g CO2/g BOD

CFCH4 = Conversion factor for maximum CH4 generation per unit BOD

= 0.5 g CH4/g BOD

MCFWW = Methane correction factor for wastewater treatment unit, indicating fraction of

the influent oxygen demand that is converted anaerobically

= 0.8 for anaerobic, 0 for aerobic

BGCH4 = Fraction of carbon as CH4 in generated biogas (default is 0.65)

λ = Biomass yield (g C converted to biomass/g C consumed)

= 0.1 for anaerobic, 0.65 for aerobic

34

In the past decomposition within a pit of a pit latrine has been considered a strictly

anaerobic process; however, one study identified during the literature review has shown that a

significant portion of the organic content may decompose aerobically before it is covered and

continues decomposing anaerobically (Bhagwan et al., 2008). This process is shown in Figure

11 which depicts the four different theoretical decomposition zones within the contents of the pit

of a latrine. The ratio of aerobic to anaerobic decomposition taking place in the pit latrine is

believed to depend on the moisture content of the material, the permeability of the surrounding

soil, the level of the water table, flow of air through the pit, and addition of other materials to the

pit (such as water for flushing, anal cleansing materials, or desiccants). The results of the

calculation in this study to determine the amount of methane and carbon dioxide emitted from a

pit latrine are presented for two cases for the pit and pour-flush latrine: (1) completely anaerobic

decomposition and (2) 50% aerobic, 50% anaerobic decomposition.

35

Equations 8 and 9 were used to calculate the mass of carbon dioxide and methane

produced by each sanitation system are provided in Table 10. These values were inputted to

SimaPro as emissions to air in the use phase of each system.

Table 10: Biogenic emissions associated with each system.

CO2 (kg) CH4 (kg)

VIP latrine 1,4001 5101

1,2702 2552

Pour-flush latrine 1,4001 5101

1,2702 2552

Composting latrine 1,140 -

Biodigester latrine 4,4603 1,7603

9,2904 -

1Assuming complete anaerobic degradation

2Assuming 50% anaerobic, 50% aerobic degradation

3Assuming biogas is not captured, and is instead released directly to air

4Assuming all biogas is captured and combusted

Figure 11: Diagram of VIP latrine showing different theoretical layers. (a) fresh stool; (b)

partially degraded aerobic surface layer; (c) partially degraded anaerobic layer beneath

surface; (d) completely stabilized anaerobic layer. Source: Buckley et al. (2008) with

permission.

36

3.4.7 Resource Recovery through Biogas and Nutrients

3.4.7.1 Biogas

The biogas produced by the biodigester is calculated using Equations 8 and 9 from the

EPA method (EPA, 2010). An 80% BOD removal efficiency has been reported as typical for the

Taiwanese style digesters (Lansing et al., 2008). This value results in the production of 2,700 m3

of methane and 2,490 m3 of CO2 over a 20-year period (or 259 m3 of biogas per year). When

accounting for the difference in energy content (35.8 MJ/m3 for methane and 39 MJ/m3 for

natural gas) (Rittmann and McCarty, 2001; McGraw-Hill, 1982), this yields an equivalent of

2,470 m3 of natural gas use avoided over the 20-year period. This value is then inputted to

SimaPro as an avoided product in the use phase of the biodigester latrine.

3.4.7.2 Biodigester Effluent

The fertilizer potential of the biodigester was determined based on the nitrogen content

of the effluent. A 222 L/day flowrate of digestate would produce16,200 m3 of effluent over a 20-

year period. Table 3 provided the nutrient concentration found in potential biodigester feeds.

The nitrogen content of the human waste was determined using the values from Table 2 (Esrey,

2000).

12.5*d

06B;7$∗2/3∗ 5.05�� ∗

?@A2/3;

36/B∗ 20#�� ∗

&<*

&=>*= 461�� (10)

The nitrogen content of the manure slurry was determined using values from ASAE

(2005). Typical cow manure slurry for household biodigesters consists of a 1:3 ratio of manure

to water. As mentioned in section 3.4.3 (Biochemical Oxygen Demand) 159 L of cow manure

slurry are added daily to satisfy the operational requirements of the biodigester.

6620K*d

F∗&FK/$:B6

LF;8:BB3∗ &AQF

2/3∗ ?@A2/3;

36/B∗ 20#�� ∗

&<*

&=eK*= 1921�� (11)

The sum of the values from Equations 10 and 11 results in 2,382 kg N produced in the

biodigester effluent over a 20-year period. This value was inputted to SimaPro as the mass of

37

urea fertilizer (as N) use avoided. Other elements present in the effluent and compost, such as

potassium and calcium, are not included in the resource recovery calculation because these

elements are not the main components of fertilizers typically used in the study site.

3.4.7.3 Compost and Urine Diversion

According to the data provided previously in Table 2, one person produces 11 g of

nitrogen in urine and 1.55 g of nitrogen in feces per day (Esrey, 2000; Jönsson et al., 2004).

Nitrogen losses associated with urine diversion, collection, and use are assumed to be

negligible because there is little opportunity for the volatilization of ammonia within a sealed

receptacle. The feces are aerobically composted within the chambers of the composting latrine.

A model for the loss of nitrogen during aerobic decomposition from Kirchman and Witter (1989)

predicts a 34.3% loss of nitrogen through the volatilization of ammonia for compost with C:N

ratio of 10 and 1-year storage time. This is within the 10-50% range suggested by Jönsson et al.

(2004) for nitrogen loss during aerobic composting. Assuming 34.3% loss of nitrogen, a

household composting latrine with urine diversion (and collection) would therefore produce 443

kg of nitrogen over a 20-year span. This value is inputted to SimaPro as urea fertilizer (as N)

use avoided in the use phase of the composting latrine.

3.5 Sensitivity Analysis

A sensitivity analysis was performed to identify changes to which input parameters the

results are more sensitive. The top five contributors in each system were considered. The value

for each input was modified by 20% and the CED and GWP of the system were calculated to

determine how the change in the input impacted the resulting CED and GWP. The percent

change in CED and GWP was then divided by the percent change of the input parameter to

determine the sensitivity factor.

38

3.6 Life Cycle Impact Assessment and Interpretation

To perform the impact assessment and interpretation steps of the life cycle, the

Cumulative Energy Demand (CED) and Global Warming Potential (GWP) methods in SimaPro

7.2 (PRé Consultants, 2008) were used to calculate the results. Embodied energy in terms of

CED (MJ) was quantified using the CED method and carbon footprint in terms of GWP (kgCO2

eq) was quantified using the Intergovernmental Panel on Climate Change (IPCC) 2007 GWP

100a method.

39

CHAPTER 4: RESULTS AND DISCUSSION

4.1 Impact of Privacy Structure on CED and GWP

The CED and GWP values of the construction phase of the four latrine designs and their

variations are provided in this section. The materials used in construction of the privacy

structure of the latrine can vary depending on location. This will change the latrine’s

environmental impact without affecting its function as a sanitation system. Many possibilities

exist in constructing a privacy structure of a latrine due to material availability, cost, and

regional/local preferences. In this study, two scenarios were chosen for comparison of the CED

and GWP contributed by the privacy shelter: (1) adobe brick walls with a fiber cement roof and

(2) brick walls with a corrugated metal roof. Table 11 provides a description of the design

variations considered in this study. Complete material inventories for each latrine are provided

in Appendix A. The CED and GWP for the construction phase, including the privacy structure

and other construction aspects, of each latrine are provided in Figure 12.

40

Table 11: Latrine design variations considered in this study.

Variation of latrine

type and privacy

shelter

Notes

VIP latrine adobe fiber

cement

• Pit lined with brick

• Adobe walls, fiber cement roof


cement (unlined pit)

• Pit unlined


VIP latrine brick

corrugated metal


• Brick walls, corrugated metal roof

Pour-flush latrine

adobe fiber cement



Pour-flush latrine brick

corrugated metal


• Brick walls, corrugated metal roof

Composting latrine

adobe fiber cement

• Chambers built from brick

• Upper walls built from adobe, fiber cement roof

Composting latrine

brick corrugated metal

• Chambers built from brick

• Upper walls built from brick, corrugated metal roof

Biodigester latrine

adobe fiber cement

• Trench reactor housing lined with adobe with concrete

inlet and outlets

• Superstructure built from adobe, fiber cement roof

Biodigester latrine

brick corrugated metal

• Trench reactor housing lined with adobe with concrete

inlet and outlets

• Superstructure walls built from brick, corrugated metal

roof

41

Figures 12a and 12b show that the unlined VIP latrine has the lowest CED and GWP

values at 760 MJ and 58.4 kgCO2 eq, respectively. There is no brick used in this design for

lining the pit or construction of the privacy structure and the CED is over 7.5 times less than the

same latrine design with a brick lined pit. Excluding the unlined VIP latrine, the CED values of

the other latrines vary between 5,724 MJ for the VIP latrine with adobe fiber cement privacy

structure and 20,474 MJ for the biodigester latrine with brick corrugated metal privacy structure.

Figure 12: (a) Cumulative energy demand and (b) global warming potential of construction

phase of sanitation systems.

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

VIP latrine Pour-flush

latrine

Composting

latrine

Biodigester

latrine

CE

D (

MJ

pe

r h

ou

seh

old

)

Adobe fiber cement

Brick corrugated

metal

Adobe fiber cement

(unlined pit)

a)

0.0E+0

5.0E+2

1.0E+3

1.5E+3

2.0E+3

VIP latrine Pour-flush

latrine

Composting

latrine

Biodigester

latrine

GW

P (

kg

CO

2e

q p

er

ho

use

ho

ld)

Adobe fiber cement

Brick corrugated

metal

Adobe fiber cement

(unlined pit)

b)

42

Designs using brick as a construction material have an average CED of 5,445 MJ higher for the

construction phase than those using adobe. The GWP values for each latrine vary between 502

kgCO2 eq for VIP latrine with adobe fiber cement privacy structure to 1,724 kgCO2 eq for the

pour-flush latrine with brick corrugated metal privacy structure. Similarly, designs using brick

have average GWP 512 kgCO2 eq higher than those using adobe. The difference between the

CED and GWP values for fiber cement and corrugated metal was negligible at (29 MJ and 7.3

kgCO2 eq, respectively). The contributions to the overall CED and GWP for each latrine are

provided in Tables 12 and 13. Complete LCA results can be found in Appendix B.

43

Table 12: Cumulative energy demand of latrine components for construction phase.

VIP latrine

adobe fiber

cement

VIP latrine

adobe fiber

cement

(unlined pit)

VIP latrine

brick

corrugated

metal

Pour-flush

latrine adobe

fiber cement

Pour-flush

latrine brick

corrugated

metal

Composting

latrine adobe

fiber cement

Composting

latrine brick

corrugated

metal

Biodigester

latrine adobe

fiber cement

Biodigester

latrine brick

corrugated

metal

Material CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

CED (MJ)

(%)

Brick 4,020

(70.2) -

8,614

(73.8)

4,020

(29.4)

8,614

(44.6)

3,446

(30.6)

6,891

(44.1)

1,723

(11.8)

6,317

(30.8)

Transport 751

(13.1)

130.7

(17.2)

1,589

(13.6)

3,788

(27.7)

4,407

(22.8)

2,483

(22.0)

3,046

(19.5)

2,929

(20.0)

3,716

(18.1)

Portland

cement

404

(7.1)

80.7

(10.6)

888

(7.6)

2,018

(14.8)

2,502

(13.0)

1,453

(12.7)

1,776

(11.4)

2,066

(14.1)

2,550

(12.4)

Fiber cement 268

(4.7)

268

(35.2) -

268

(2.0) -

268

(2.4) -

268

(1.8) -

Corrugated

metal - -

297

(2.5) -

297

(1.5) -

297

(1.9) -

297

(1.5)

Sanitary

ceramics - - -

1,942

(14.2)

1,942

(10.1)

1,349

(12.0)

1,349

(8.6)

1,942

(13.3)

1,942

(9.5)

PVC pipe 92

(1.6)

92

(12.2)

92

(0.8)

524

(3.8)

524

(2.7)

644

(5.7)

644

(4.1)

861

(5.9)

861

(4.2)

PVC

geomembrane - - - - - - -

2,665

(18.2)

2,665

(13.0)

Other 189

(3.3)

189

(24.9)

189

(1.6)

1,108

(8.1)

1,010

(5.2)

1,633

(14.5)

1,633

(10.4)

2,175

(14.9)

2,139

(10.4)

Total 5,724

(100)

760

(100)

11,668

(100)

13,667

(100)

19,295

(100)

11,275

(100)

15,636

(100)

14,628

(100)

20,474

(100)

44

Table 13: Global warming potential of latrine components for construction phase.

VIP latrine adobe and

fiber cement



VIP latrine brick

corrugated metal

Pour-flush latrine adobe fiber cement

Pour-flush latrine brick corrugated

metal

Composting latrine adobe fiber cement

Composting latrine brick corrugated

metal

Biodigester latrine adobe fiber cement

Biodigester latrine brick corrugated

metal

Material GWP

(kgCO2 eq) (%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

GWP (kgCO2 eq)

(%)

Brick 338

(67.3) -

724 (66.8)

338 (28.3)

724 (42.0)

290 (30.7)

579 (43.2)

145 (13.4)

531 (33.2)

Transport 43.2 (8.6)

7.5 (12.9)

127 (11.7)

218 (18.2)

253 (14.7)

143 (15.1)

175 (13.0)

211 (16.6)

214 (13.3)

Portland cement

87.3 (17.4)

17.5 (29.9)

192 (17.7)

436 (36.5)

541 (31.4)

314 (33.3)

384 (28.6)

447 (41.2)

551 (34.5)

Fiber cement 19.9 (4.0)

19.9 (34.1)

- 19.9 (1.7)

- 19.9 (2.1)

- 19.9 (1.8)

-

Corrugated metal

- - 27.2 (2.5)

- 27.2 (1.6)

- 27.2 (2.0)

- 27.2 (1.7)

Sanitary ceramics

- - - 106 (8.9)

106 (6.1)

73.5 (7.8)

73.5 (5.5)

106 (9.8)

106 (6.6)

PVC pipe 4.4

(0.9) 4.4

(7.5) 4.4

(0.4) 24.9 (2.1)

24.9 (1.4)

30.6 (3.2)

30.6 (2.3)

41.0 (3.8)

41.0 (2.6)

PVC geomembrane

- - - - - - - 87.3 (8.1)

87.3 (5.4)

Other 9.1

(1.8) 9.1

(15.7) 9.1

(0.8) 51.5 (4.3)

47.8 (2.8)

72.7 (7.7)

72.7 (5.4)

69.9 (6.4)

63.1 (3.9)

Total 502

(100) 58.4 (100)

1,084 (100)

1,194 (100)

1,724 (100)

943 (100)

1,342 (100)

1,084 (100)

1,620 (100)

45

In general, the main contributors to the CED and GWP of the construction phase of each latrine

are brick, transport, and cement which on average account for 41.9%, 19.3%, and 11.5% of the

CED and 40.6%, 13.8%, and 30.1% of the GWP, respectively.

4.2 CED and GWP Associated with Use Phase and Resource Recovery

In this section the CED and GWP of the construction and use phases of each latrine

over a 20-year period are examined. Different use phase scenarios are considered and the

adobe and fiber cement privacy structure is considered for the construction phase. Figure 13

provides the CED values with and without resource recovery of each sanitation system.

The VIP and pour-flush latrine do not feature resource recovery and, therefore the same

value is presented in Figure 13a and 13b with and without resource recovery (11,447 MJ and

18,464 MJ, respectively). Resources are recovered in the composting latrine and biodigester

Figure 13: Cumulative energy demand of four sanitation systems over a 20-year period (a)

without resource recovery and (b) with resource recovery. Note: VIP and pour-flush latrine do

not recover resources and their CED values are repeated for comparison. Resource recovery

of the biodigester latrine is based on the combined input from the household latrine and cow

manure slurry.

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

CE

D (

MJ

pe

r h

ou

seh

old

)

VIP latrine

Pour-flush latrine

Composting latrine

Biodigester latrine

a)

-2.50E+5

-2.00E+5

-1.50E+5

-1.00E+5

-5.00E+4

0.00E+0

5.00E+4

CE

D (

MJ

pe

r h

ou

seh

old

)

VIP latrine

Pour-flush latrine

Composting latrine

Biodigester latrine

b)

46

latrine through use of the compost and effluent as soil amendments (and fertilizers) and in the

case of the biodigester latrine, through use of the biogas as fuel source for cooking. These

values are quantified in terms of the avoided products associated with them, i.e., the nitrogen

fertilizer (urea) and natural gas use avoided. These resource recovery scenarios are considered

ideal; that is, all of the nitrogen found in the compost, diverted urine, and biodigester effluent is

directly replacing and equivalent amount of commercial nitrogen fertilizer. Thus the results are

presented for the maximum use avoided. These results along with the other contributors to the

overall CED values for each latrine are provided in Table 14.

In Table 14, the CED values of the systems without resource recovery range between

11,275 MJ and 19,990 MJ. However, when resource recovery is considered, as shown in Figure

13b and Table 14, the composting and biodigester latrines become net energy producers over

the 20-year period. In fact, the biodigester latrine recovers over 12 times the amount of energy

than it requires for construction and maintenance. The large values for resource recovery for the

Table 14: Contributions to cumulative energy demand of four sanitation systems that consider

resource recovery over 20-year life.

VIP

latrine

Pour-

flush

latrine

Compostin

g latrine

without

resource

recovery

Compostin

g latrine

with

resource

recovery

Biodigeste

r latrine

without

resource

recovery

Biodigeste

r latrine

with

resource

recovery

CED

(MJ)

CED

(MJ)

CED

(MJ)

CED

(MJ)

CED

(MJ)

CED

(MJ)

Construction

phase 5,724 13,667 11,275 11,275 14,628 14,628

Use phase

(maintenanc

e)

5,724 4,798 - - 5,362 5,362

Fertilizer use

avoided (N) - - - -29,333 - -157,865

Natural gas

use avoided - - - - - -95,325

Total 11,447 18,464 11,275 -18,058 19,990 -233,200

47

biodigester latrine are due to combined BOD input to the system from the household latrine and

the cow manure slurry. This total combined input was calculated as 3.2 times the input from only

a household latrine in terms of BOD content. The fertilizer use avoided of the biogas accounts

for 62.4% of the overall resource recovery potential of the biodigester latrine while the natural

gas use avoided of the biogas accounts for 37.6%.

Like the CED, the GWP of each system is based on the material inputs from the

construction, maintenance, avoided products due to resource recovery, but also includes the

contribution from biogenic emissions. As shown in section 3.4.6 (Biogenic Emissions), the

results are presented for the degradation of the waste within the pit of the VIP and pour-flush

latrines as either 100% anaerobic or 50% aerobic/50% anaerobic. 100% aerobic degradation is

assumed to take place within the composting latrine. Three scenarios are considered for the use

phase of the biodigester latrine which affect its biogenic emissions and avoided products: (1) the

system is operated without resource recovery, i.e., the biogas is not captured, and instead is

released directly to the air and the effluent is not used as fertilizer, (2) the system is operated

without resource recovery; however, the biogas is captured and combusted, but not used for

cooking (i.e., flared or burned in biogas lamp), and (3) the system is operated with resource

recovery, i.e., the biogas is captured and used for cooking and the effluent is used as fertilizer,

replacing commercial fertilizer. Figure 14 provides the GWP of each latrine with and without

resource recovery.

48

Again, the VIP and pour-flush latrine are not designed to recover resources and their

GWP values are reproduced in Figure 14b for comparison. In general, the biogenic emissions,

specifically methane which is 25 times more powerful than carbon dioxide as a greenhouse gas,

dominate the overall GWP of each latrine. When anaerobic degradation takes place, the sludge

is converted to methane and carbon dioxide, whereas aerobic degradation produces only

carbon dioxide. The GWP of the biodigester latrine operated without resource recovery is over 3

times higher than the next highest system. This is because not only human waste, but also cow

manure is contributing to the biogenic emissions. When operated with resource recovery,

household sanitation systems have relatively small carbon footprint compared to systems

without resource recovery. For example, the GWP of the composting latrine is reduced from

2,079 kgCO2 eq to 616 kgCO2 eq when resource recovery is considered. In the case of the

biodigester the GWP is reduced from 49,655 kgCO2 eq without resource recovery to 10,562

kgCO2 eq if the biogas is simply flared or 1,882 kgCO2 eq with resource recovery. The

contributions to the overall GWP of each latrine is provided in Table 15.

Figure 14: Global warming potential of four sanitation systems over a 20-year period (a)

without resource recovery and (b) with resource recovery. Biogenic emissions and resource

recovery of the biodigester latrine is based on the combined input from the household latrine

and cow manure slurry.

0E+0

1E+4

2E+4

3E+4

4E+4

5E+4

GW

P (

kg

CO

2 e

q p

er

ho

use

ho

ld)

VIP Latrine (100% anaerobic)

VIP latrine (50% anaerobic)

Pour-flush latrine (100% anaerobic)


Composting latrine

Biodigester latrine

Biodigester latrine (with flaring)

a)

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

GW

P (

kg

CO

2 e

q p

er

ho

use

ho

ld)





Composting latrine

Biodigester latrine

b)

49

Table 15: Contributions to global warming potential of sanitation systems over 20-year life.

VIP latrine1 VIP latrine

2

Pour-flush

latrine1

Pour-flush

latrine2

Composting

latrine

without

resource

recovery

Composting

latrine with

resource

recovery

Biodigester

latrine

without

resource

recovery3

Biodigester

latrine with

resource

recovery4

Biodigester

latrine

without

resource

recovery

with

flaring4

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

GWP

(kgCO2 eq)

(%)

GWP

(kgCO2 eq)

GWP

(kgCO2 eq)

(%)

Construction

phase

502

(3.3)

502

(3.3)

1,211

(7.7)

1,211

(12.9)

943

(45.4) 943

1,084

(2.2) 1,084

1,084

(10.3)

Use phase

(maintenance)

502

(3.3)

502

(3.3)

453

(2.9)

453

(4.8)

186

(0.4) 186

186

(1.8)

Direct CH4 12,741

(84.1)

6,370

(73.7)

12,741

(80.7)

6,370

(67.9) - -

43,926

(88.5) - -

Direct CO2 1,401

(9.2)

1,268

(14.7)

1,401

(8.9)

1,268

(13.5)

1,135

(54.6) 1,135

4,460

(9.0) 9,293

9,293

(88.0)

Fertilizer use

avoided (N) - - - - - -1,462 - -7,869 -

Natural gas

use avoided - - - - - - - -811 -

Total 15,146

(100)

8,642

(100)

15,789

(100)

9,286

(100)

2,079

(100) 616

49,655

(100) 1,882

10,562

(100) 1Assuming complete anaerobic degradation




In general, the biogenic emissions dominate the overall GWP of each latrine

contribution of biogenic emissions to the GWP is lowest for the composting latrine at 1,135

kgCO2 eq, or 54.6% of the overall GWP

taking place within the composting latrine which produces on

contributions of biogenic emissions, maintenance and construction

latrine are also presented in Figure 1

of the systems; however, one study done on thermophilic composting of swine wasting

measured only a 30% reduction of the total organic carbon due to thermophilic composting of

swine waste (Zhu, 2007). Using a 30% BOD removal efficiency, the biogenic CO

the composting latrine would be 426 kgCO

efficiency.

Figure 15: Contribution of materials and biogenic emissions to global

each sanitation system. 1Assuming complete anaerobic degradation




0.0E+0

1.0E+4

2.0E+4

3.0E+4

4.0E+4

5.0E+4

GW

P (

kg

CO

2e

q)

50

In general, the biogenic emissions dominate the overall GWP of each latrine


% of the overall GWP. This is due to the strictly aerobic biochemical

taking place within the composting latrine which produces only carbon dioxide. The

of biogenic emissions, maintenance and construction to the overall GWP of each

ed in Figure 15. An 80% BOD removal efficiency was assumed for each



Using a 30% BOD removal efficiency, the biogenic CO

the composting latrine would be 426 kgCO2 eq compared to 1,135 kgCO2 eq with an 80%

of materials and biogenic emissions to global warming potential for

Assuming complete anaerobic degradation

Assuming 50% anaerobic, 50% aerobic degradation

Assuming biogas is not captured, and is instead released directly to air

Assuming all biogas is captured and combusted

Use phase

(maintenanc

e)Construction

Direct carbon

dioxide

In general, the biogenic emissions dominate the overall GWP of each latrine. The


biochemical process

The

to the overall GWP of each

An 80% BOD removal efficiency was assumed for each



Using a 30% BOD removal efficiency, the biogenic CO2 emissions of

eq with an 80%

warming potential for

Use phase

(maintenanc

Construction

Direct carbon

51

4.3 CED and GWP of Household and Community-Level Sanitation Systems

The CED and GWP of two community wastewater treatment systems in rural Bolivia

were studied by Cornejo et al. (2013). The community system of Sapecho serves a sewered

community of 1,039 people (206 households) and includes a grit chamber, upflow anaerobic

sludge blanket (UASB) reactor and two maturation lagoons. The community system of San

Antonio serves a sewered community of 420 people (150 households) and includes a three-

pond system (one facultative and two maturation lagoons). Both systems are currently operated

without resource recovery, but the calculations made by Cornejo et al. (2013) are based on

potential use phases implementing resource recovery. In the case the community system of

Sapecho, resource recovery is associated with the recovery of biogas produced by the UASB

reactor and reuse of the system’s effluent for irrigation. For the community system of San

Antonio resource recovery is only associated with reuse of the system’s effluent for irrigation.

The results from this study on community systems in terms of CED are provided in Figure 16

along with the results for household systems discussed in the previous section that are

presented for comparison.

Figure 16a shows that the

without resource recovery (41,738 MJ

household systems without resource recovery (15,294 MJ

material inputs of the infrastructure of the community

location the collection system alone

community systems of Sapecho

Resource recovery was interpreted slightly

systems which may lead to different contributions to the CED and GWP for each system in the

resource recovery condition. For example,

terms of an equivalent mass (based on energy content) of natural gas use avoided while in the

case of the community system of

system. Likewise, the effluent and compost

the avoided use of urea fertilizer

systems the use of the system effluent is indirectly quantified in terms of t

Figure 16: Cumulative energy demand of household and community level sanitation systems

per household over 20-year period (a)

recovery.

0E+0

1E+4

2E+4

3E+4

4E+4

5E+4

CE

D (

MJ

pe

r h

ou

seh

old

)

VIP latrine

Pour-flush latrine

Composting latrine

Biodigester latrine

Community system (Sapecho)

Community system (San Antonio)

a)

52

he average CED per household of the community systems

resource recovery (41,738 MJ) is 2.7 times more than the average CED of the

resource recovery (15,294 MJ). This is because of the

infrastructure of the community collection system. For example, in this

he collection system alone accounts for 41% and 49% of the overall CED of

and San Antonio, respectively.

interpreted slightly differently for the household and community

different contributions to the CED and GWP for each system in the

For example, the biogas for the household system is


of Sapecho biogas itself is considered a co-product of the

system. Likewise, the effluent and compost of the household systems are modeled in terms of

fertilizer with an equivalent mass of nitrogen while in the community

effluent is indirectly quantified in terms of the river water use for

: Cumulative energy demand of household and community level sanitation systems

year period (a) without resource recovery and (b) with resource

Composting latrine

Biodigester latrine



-2.5E+5

-2.0E+5

-1.5E+5

-1.0E+5

-5.0E+4

0.0E+0

5.0E+4

CE

D (

MJ

pe

r h

ou

seh

old

)

VIP latrine

Pour-flush latrine

Composting latrine

Biodigester latrine



b)

CED per household of the community systems

average CED of the

the higher

For example, in this

CED of

for the household and community

different contributions to the CED and GWP for each system in the

usehold system is considered in


product of the

of the household systems are modeled in terms of

nitrogen while in the community

he river water use for

: Cumulative energy demand of household and community level sanitation systems

out resource recovery and (b) with resource



irrigation avoided and crop yield increases

fertilizer is not commonly used in agriculture in the Bolivian study site.

resource recovery potential for the use of the effluent in the community

underestimated compared to the resource recovery potential of the use of the compost and

household biodigester effluent. Figure 1

systems with resource recovery are 44,869 MJ for Sapecho and

Figure 17 provides the global warming potential of household and community level

sanitation systems per household over 20

Similar to the case of household latrines,

biogenic emissions that are the main contributors to the overall

Biogenic emissions account for 67% of the overall

resource recovery and 53% of the overall GWP of

Figure 17: Global warming potential of household and community level sanitation systems

household over 20-year period (a)

0E+0

1E+4

2E+4

3E+4

4E+4

5E+4

GW

P (

kg

CO

2 e

q p

er

ho

use

ho

ld)





Composting latrine

Biodigester latrine

Biodigester latrine (w/ flaring)



53

and crop yield increases. This was done because commercial nitrogen

fertilizer is not commonly used in agriculture in the Bolivian study site. It is thus

resource recovery potential for the use of the effluent in the community systems is


Figure 16b shows that the CED per household of the community

systems with resource recovery are 44,869 MJ for Sapecho and 38,403 MJ for San Antonio.

provides the global warming potential of household and community level

sanitation systems per household over 20-years.

Similar to the case of household latrines, the results in Figure 17 are influenced by

are the main contributors to the overall GWP of the community systems.

Biogenic emissions account for 67% of the overall GWP of the Sapecho system

resource recovery and 53% of the overall GWP of San Antonio system. Impleme

lobal warming potential of household and community level sanitation systems

year period (a) without resource recovery and (b) with resource recovery



flush latrine (100% anaerobic)


Biodigester latrine (w/ flaring)



a)

0.00E+0

2.50E+3

5.00E+3

7.50E+3

1.00E+4

1.25E+4

1.50E+4

1.75E+4

GW

P (

kg

CO

2 e

q p

er

ho

use

ho

ld)





Composting latrine

Biodigester latrine



This was done because commercial nitrogen

likely that the

systems is


of the community

for San Antonio.

provides the global warming potential of household and community level

are influenced by

GWP of the community systems.

WP of the Sapecho system without

Implementation of

lobal warming potential of household and community level sanitation systems per

and (b) with resource recovery.







b)

54

combined resource recovery in the Sapecho system (recovery of biogas and irrigation with

system effluent) was estimated to reduce the overall GWP from 4,930 kgCO2 eq to 2,092 kgCO2

eq, or 58.4%. In the case of the San Antonio system, implementation of resource recovery

(irrigation with system effluent) was estimated to reduce the overall GWP from 2,022 kgCO2 eq

to 2,019 kgCO2 eq., or 0.1%. The community systems have a lower GWP per household than

the conventional household latrines that do not recover resources, i.e., VIP and pour-flush

latrine, but have a slightly higher GWP than household systems that incorporate resource

recovery. Similarly, a study by Fuchs and Mihelcic (2011) in the same study site in Bolivia as

Cornejo et al. (2013) determined that decentralized or semi-decentralized sanitation systems,

such as condominial sewer systems, most closely satisfied the appropriate technology

characteristics measured.

The BOD input was calculated slightly differently for the household and community

systems. As mentioned in section 3.4.3 (Biochemical Oxygen Demand Input), the BOD input

value for the household systems is based on the value of BOD production rate per capita of 80

g BOD/person-day typically used in the wastewater design literature (Metcalf and Eddy, 2003).

For the community treatment systems, the BOD input was based on actual field measurements

of the influent wastewater. These values, when converted to a BOD production rate per capita

result in a value of only 16 g BOD/person-day for the Sapecho system and 27 g/person-day for

the San Antonio system. These values are 3-5 times lower than the literature value for

conventional wastewater treatment design likely due to the fact that the wastewater does not

include food waste and that it is a largely agricultural area where people may not have access to

residential bathrooms during the work day. This leads to subsequently lower values for the

biogenic emissions and biogas production for the community systems compared to the

household systems.

55

4.4 Sensitivity Analysis

Sensitivity factors (SFs) for the privacy structure results are provided in Table 16 and for

the use phase and resource recovery results in Table 17. Larger sensitivity factors indicate

greater sensitivity in the results to changes in input values and vice versa.

For both the privacy structure and use phase results, the most sensitive items in terms of

embodied energy include: brick, transport, cement, and the PVC geomembrane, in the case of

the biodigester latrine. Their high contribution of these input parameters to the total embodied

energy (27-95%) may be the reason they are more sensitive. Individual contributions to CED

are provided in Appendix B. Future studies can refine these input values to improve the

accuracy of the model.

When considering only the privacy structure results, the most sensitive items in terms of

carbon footprint are similar to those of embodied energy: brick, transport, and cement, which

account for between 42-96% of the total GWP. However, when considering the use phase, the

most sensitive items are the biogenic emissions of methane and carbon dioxide, which account

for between 50-97% of the GWP, followed by brick, transport, and cement. Future research

refining the calculation in terms of the actual biogenic emissions associated with each system,

and to a lesser extent material inputs, would improve the accuracy of the model.

It is possible that in the study site the biogas, when used for cooking, would actually

replace propane rather than natural gas. The energy ladder that is commonly used to explain

how households advance to cleaner and more expensive forms of energy from solid fuels

considers propane and natural gas usage at a similar level of development (Smith et al., 1994).

However, if one considers the resource recovery potential of the biogas as propane use avoided

rather than natural gas use avoided affects the results for CED and GWP. The overall CED for

the biodigester latrine using propane use avoided for the biogas is 8.8% higher (- 212,700 MJ)

than in terms of natural gas use avoided (- 233,200 MJ). The GWP for the biodigester latrine is

56

7.7% lower with the biogas considered in terms of propane use avoided (1,740 kgCO2 eq) than

when considered as natural gas use avoided (1,880 kgCO2 eq).

57

Table 16: Sensitivity factors for privacy shelter (construction phase) results.

Variation of latrine type

and privacy shelter

Input SF of

CED

SF of

GWP


cement

Brick 0.703 0.673

Transport 0.131 0.085

Cement 0.070 0.174

Fiber cement 0.048 0.040

PVC pipe 0.013 0.010



Fiber cement 0.352 0.337


PVC pipe 0.122 0.085

Cement 0.108 0.299

Plywood 0.069 0.017

VIP latrine brick corrugated

metal

Brick 0.738 0.690


Cement 0.076 0.183

Corrugated metal 0.026 0.026

PVC pipe 0.008 0.004

Pour-flush latrine adobe fiber

cement

Brick 0.294 0.283


Cement 0.148 0.365

Sanitary ceramics 0.142 0.089

PVC pipe 0.039 0.021

Pour-flush latrine brick

corrugated metal

Brick 0.442 0.420


Cement 0.128 0.314


PVC pipe 0.027 0.015

Composting latrine adobe

fiber cement

Brick 0.306 0.307


Cement 0.129 0.333


PVC pipe 0.057 0.032

Composting latrine brick

corrugated metal

Brick 0.441 0.432


Cement 0.114 0.286


PVC pipe 0.041 0.023

Biodigester latrine adobe

fiber cement


Geomembrane PVC 0.186 0.082

Cement 0.144 0.417


Brick 0.120 0.135

Biodigester latrine brick

corrugated metal

Brick 0.309 0.328



Cement 0.125 0.340


58

Table 17: Sensitivity factors for construction and use phase results.

Latrine type and use

phase

Input SF of

CED

SF of

GWP


cement (100% anaerobic)

Biogenic CH4 - 0.841

Biogenic CO2 - 0.093

Brick 0.704 0.045


Cement 0.071 0.012


cement (50% anaerobic,

50% aerobic)



Brick 0.704 0.045


Cement 0.071 0.012


cement (100% anaerobic)



Brick 0.439 0.043


Cement 0.158 0.040


cement (50% anaerobic,

50% aerobic)



Brick 0.451 0.073


Cement 0.163 0.057

Composting latrine adobe

fiber cement without

resource recovery


Brick 0.306 0.139


Cement 0.129 0.151




resource recovery





Cement 0.105 0.009



resource recovery with

flaring




Cement 0.105 0.042


59

CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH

The original hypothesis proposed in this thesis that sanitation systems that incorporate

resource recovery will have higher CED than systems that do not recover resources due to

additional material requirements during installation and maintenance, but will have lower GWP

over their service life than those that do not. The first point of this hypothesis implies that

additional material inputs are required to allow for resource recovery. Based on the results of

this study, this is not correct. When only the construction phase is considered there is no

correlation between the CED values of sanitation systems that incorporate resource recovery

and those that do not. The VIP latrine had the lowest CED (5,724 MJ), followed by the

composting latrine (11,275 MJ), the pour-flush latrine (13,667 MJ), and the biodigester latrine

(14,628 MJ). However, when the use phase is considered the energy recovered through

resource recovery more than offsets the energy required for construction and maintenance of

both the composting and biodigester latrine. The composting latrine requires 11,275 MJ for

construction and maintenance and recovers 29,933 MJ through use of the compost as a

fertilizer substitute. The biodigester latrine requires 19,990 MJ for construction and maintenance

and recovers 253,190 MJ through use of the effluent as a fertilizer substitute and the biogas as

a substitute for natural gas for cooking. Therefore, both the composting and biodigester latrine

are net energy producers over a 20-year period. Although they are not carbon neutral, their

GWP of the systems incorporating resource recovery is considerably lower than the GWP of

systems that do not. For example, the composting latrine has a GWP of 616 kgCO2 eq and the

biodigester latrine has a GWP of 1,882 kgCO2 eq compared to 15,146 kgCO2 eq and 15,789

kgCO2 eq for the VIP latrine and pour-flush latrine, respectively.

60

The second hypothesis proposed in this thesis was that community systems that

incorporate a collection system have a higher CED than household systems due to the material

input requirements associated with the infrastructure of the system. Based on the results of this

study this hypothesis is true. The CED values of the community systems of Sapecho (44,869

MJ per household) and San Antonio (38,403 MJ per household) with resource recovery were

higher than the CED of any household sanitation systems with or without resource recovery

(which ranged between 11,275 and 19,990 MJ). This result is because of the contribution of the

collection system to the (which accounts for an average of 18,600 MJ per household) to the

overall CED of the community systems. Interestingly, the GWP of community systems (2,019-

2,092 kgCO2 eq) is less than the GWP of household systems that do not incorporate resource

recovery (8,642-15,789 kgCO2 eq) and slightly more than household systems that recover

resources (616-1,882 kgCO2 eq).

As expected, the use of local materials in the construction of the privacy structure

improves the environmental sustainability of the systems. Adobe brick is prepared manually at

the construction site and dried in the sun while brick that is produced off-site in an industrial

process has large energy input requirements. Design variations and material use have a large

impact on the results in terms of CED. The main contributor to the GWP over the lifetime of

these systems is the biogenic emissions, specifically for those that produce methane.

There is little data available about the actual biochemical processes taking place with the

pit of a VIP or pour-flush latrine. Recent research suggests a combination of aerobic and

anaerobic decomposition takes place within the pit; however, future research could more

precisely determine the ratio of these processes occurring in the pit to allow for more accurate

calculation of the associated biogenic emissions over the life of the latrine.

In addition, the service life of the Taiwanese tubular biodigester in the field can vary

depending on maintenance and protection of the geomembrane from mechanical failure.

Improperly operated or maintained biodigesters can produce significantly higher greenhouse

61

gas emissions due to biogas leaks. Future studies can more precisely determine this

technology’s service life and when applied in rural areas of developing countries and allow for

more accurate description its potential to mitigate the effects of climate change.

62

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68

APPENDICES

69

Appendix A Material Inventories

Table A.1: Material inventory for VIP latrine adobe fiber cement privacy structure

Material Unit Quantity Volume (m3) Density (kg/m3) Mass (kg) Mode of Transport Origin Distance (km)

CEMENT PORTLAND TYPE I (42.5 kg) BAG 2.50 0.05 2300.00 106.25 Camion Pacasmayo 449

SAND, COURSE m3 0.05 0.05 1600.00 80.00 Camion Morropon 45.5

STONE 1" TO 2" m3 0.03 0.03 2515.00 75.45 Camion Morropon 45.5

WIRE, BLACK NO. 16 kg 0.25

0.25 Camion Piura 130

REBAR 3/8" 9 m UNIT 1.00 6.41E-04 7850.00 5.03 Camion Lima 1108

WOOD BEAMS FOR FOUNDATION 2"x4"x1.8m UNIT 4.00 3.78E-03 670.00 2.53 N/A Local 0

VENTILATION HAT, PVC 4" UNIT 1.00


TUBE, PVC 4" 3 m m 1.00


ADOBE BRICK (30x30x10cm) UNIT 300.00 0.01 1515.11 4090.80 N/A Local 0

BRICK (22x12x8 cm) UNIT 350 2.11E-03 1922.00 1420.74 Camion Buenos Aires 63.1

NAILS FOR ETERNIT ROOF UNIT 3.00


ETERNIT ROOF, GRAY 8" FIBRE CEMENT UNIT 2.50 8.96E-03 1300.00 29.13 Camion Piura 130

PLYWOOD ft2 30.00 1.39E-03

3.01 Camion Lima 1108

NAIL WITH "HAT" 2.5" kg 0.50


WOOD BEAMS FOR FRAME UNIT 4.00

Included in other items N/A Local 0

WOOD BEAMS FOR ROOF UNIT 4.00

Included in other items N/A Local 0

SHEET METAL DOOR WITH FRAME, PADLOCK, AND RINGS (1.83m x 0.87m) UNIT 1.00

included in other items Camion Piura 130

PLASTER, 20 kg BAG 0.05


70

Appendix A (Continued)

Table A.2: Material inventory for VIP latrine brick corrugated metal privacy structure











TUBE, PVC 4" 3 m m 1.00



CORRUGATED METAL (2.4x0.8 m) UNIT 2.5


PLYWOOD ft2 30.00 1.39E-03

- Camion Lima 1108




included in other items N/A Local 0







71


Table A.3: Material inventory for VIP latrine adobe fiber cement privacy structure (unlined pit)











TUBE, PVC 4" 3 m m 1.00






ETERNIT ROOF, GRAY 8" FIBRE CEMENT UNIT 2.50 8.96E-03 1300.00 29.13 Camion Piura 130

PLYWOOD ft2 30.00 1.39E-03












72


Table A.4: Material inventory for pour-flush latrine adobe fiber cement privacy structure




SAND, FINE m3 0.74 0.74 1600.00 1190.40 Camion Morropon 45.5

STONE 1/2" TO 3/4" m3 1.73 1.73 2515.00 4888.26 Camion Morropon 45.5

MIXED AGGREGATE, SAND AND STONE m3 1.11 1.11 1922.00 included in other

item Camion Morropon 45.5








ETERNIT ROOF, GRAY 8" FIBRE CEMENT UNIT 2.50 8.96E-03 1300.00 29.13 Camion Lima 1108

ADOBE BRICKS (30x30x10cm) UNIT 300.00 0.01 1515.11 4090.80 N/A Local 0

BRICK (22x12x8 cm) UNIT 350.00 2.11E-03 1922.00 1420.74 Camion Buenos Aires 63.1

PLYWOOD ft2 30.49 0.0014 670.00 - N/A Local 0

WOOD BEAMS 4"x4"x1.5 m UNIT 4.00 0.0155 670.00 - N/A Local 0

HINGE 3" UNIT 3.00


DOOR KNOB UNIT 1.00


NAILS FOR WOOD C/C 1" kg 0.10






NYLON MESH, MOSQUITO m2 0.24


TOILET, PREFABRICATED UNIT 1.00


SINK, PREFABRICATED UNIT 1.00


TOILET SEAT (PLASTIC) UNIT 1.00


PLASTER 16 kg BAG BAG 0.29


CONCRETE BOX FOR CONTROL VALVE UNIT 1.00


VALVE PVC 1/2" UNIT 1.00


ADAPTOR, PVC 1/2" UNIT 3.00


73


Table A.4: (Continued) TUBE, PVC 1/2" 5m UNIT 1.00


FAUCET, BRONZE 1/2" UNIT 1.00


ELBOW, PVC 90 1/2" UNIT 2.00


TEE, PVC 1/2" UNIT 1.00


TUBE, PVC 2" m 3.08


TUBE, PVC 4" m 7.21




ELBOW, PVC 90 2" UNIT 1.00




TEE PVC SAL 4"x2" UNIT 1.00


Table A.5: Material inventory for pour-flush latrine brick corrugated metal privacy structure




SAND, FINE m3 0.74 0.74 1600.00 1190.40 Camion Morropon 45.5

STONE 1/2" TO 3/4" m3 1.73 1.73 2515.00 4888.26 Camion Morropon 45.5

MIXED AGGREGATE, SAND AND STONE m3 1.11 1.11 1922.00 included in other










PLYWOOD ft2 30.49 0.0014 670.00

N/A Local 0

WOOD BEAMS 4"x4"x1.5 m UNIT 4.00 0.0155 670.00

N/A Local 0

74


Table: A.5 (Continued)

HINGE 3" UNIT 3.00


DOOR KNOB UNIT 1.00
















PLASTER 16 kg BAG BAG 0.29


PAINT, OCRE kg 2.36








TUBE, PVC 1/2" 5m UNIT 1.00






TEE, PVC 1/2" UNIT 1.00


TUBE, PVC 2" m 3.08


TUBE, PVC 4" m 7.21








TEE PVC SAL 4"x2" UNIT 1.00


75


Table A.6: Material inventory for composting latrine adobe fiber cement privacy structure


ADOBE BRICK (0.3x0.3x0.1 m) UNIT 300 9.00E-03 1515.11 4090.80 N/A Local 0


SAND, SIFTED m3 0.378 0.38 1600.00 604.80 Camion Morropon 45.5

WOOD, 3 m (3 cm diameter) PIECE 3 6.36E-07 670.00

N/A Local 0

WOOD, 2.4 m (3 cm diameter) PIECE 3 5.09E-07 670.00

N/A Local 0

WOOD, 2"x0.25x1.5 m PIECE 1 1.91E-02 670.00

N/A Local 0

STONE, CRUSHED m3 0.855 0.86 2515.00 2150.33 Camion Morropon 45.5

STONE, MEDIUM m3 0.414 0.41 2515.00 1041.21 Camion Morropon 45.5

CEMENT PORTLAND TYPE I (42.5 kg) BAG 9

2300.00 382.50 Camion Pacasmayo 449

REBAR 1/2" 9 m UNIT 3 1.14E-03 7850.00 26.85 Camion Lima 1108


WIRE No. 16 kg 1.5



TUBE, PVC 8" 5 m UNIT 0.14




ELBOW, PVC 2" 90 UNIT 6


TEE, PVC 2" UNIT 1


TEE, PVC 4" UNIT 1




TUBE, DESAGUE BLACK 4" 3 m UNIT 1


VENTILATION HAT, PVC 4" UNIT 1


NYLON MESH m2 0.26


PLYWOOD ft2 30 0.0014 670.00 0.93 Camion Piura 130

76


Table A.6: (Continued)

RUBBER m2 0.05 1.50E-04 1522.00 0.23 Camion Piura 130

HINGE, 3" WITH SCREWS UNIT 5


LATCH, 1.5" UNIT 2


ETERNIT ROOF, GRAY 8" FIBRE CEMENT UNIT 2.50 8.96E-03 1300.00 29.13 Camion Lima 1108

TOILET SEAT (PLASTIC) UNIT 2


URINAL (PORCELAIN) UNIT 1


SEPARATOR SEAT (FIBER GLASS) UNIT 2


PLASTIC SHEET (DOUBLE WIDE 1.5) m 3


Table A.7: Material inventory for composting latrine brick corrugated metal privacy structure



SAND, SIFTED m3 0.378 0.38 1600.00 604.80 Camion Morropon 45.5

WOOD, 3 m (3 cm diameter) PIECE 3 6.36E-07 670.00 - N/A Local 0

WOOD, 2.4 m (3 cm diameter) PIECE 3 5.09E-07 670.00 - N/A Local 0

WOOD, 2"x0.25x1.5 m PIECE 1 1.91E-02 670.00 - N/A Local 0

STONE, CRUSHED m3 0.855 0.86 2515.00 2150.33 Camion Morropon 45.5

STONE, MEDIUM m3 0.414 0.41 2515.00 1041.21 Camion Morropon 45.5

CEMENT PORTLAND TYPE I (42.5 kg) BAG 11

2300.00 467.50 Camion Pacasmayo 449

REBAR 1/2" 9 m UNIT 3 1.14E-03 7850.00 26.85 Camion Lima 1108


WIRE No. 16 kg 1.5





77







TEE, PVC 2" UNIT 1


TEE, PVC 4" UNIT 1




TUBE, DESAGUE BLACK 4" 3 m UNIT 1


VENTILATION HAT, PVC 4" UNIT 1


NYLON MESH m2 0.26


PLYWOOD ft2 30 0.0014 670.00 0.93 Camion Piura 130

RUBBER m2 0.05 1.50E-04 1522.00 0.23 Camion Piura 130

HINGE, 3" WITH SCREWS UNIT 5


LATCH, 1.5" UNIT 2




DOOR KIT (WOOD WITH SCREWS) KIT 1 4.48E-03 670.00 3.00 Camion Piura 130

TOILET SEAT (PLASTIC) UNIT 2


URINAL (PORCELAIN) UNIT 1


SEPARATOR SEAT (FIBER GLASS) UNIT 2


PLASTIC SHEET (DOUBLE WIDE 1.5) m 3


78


Table A.8: Material inventory for biodigester latrine adobe fiber cement privacy structure


REACTOR 10m3 (8x1.42 m) GEOMEMBRANE 0.6 mm thick UNIT 1.00 2.24E-02 1400.00 34.00 Camion Lima 1108

GAS RESERVOIR (2.2x0.9 m) UNIT 1.00 4.50E-03 1400.00 10.00 Camion Lima 1108

PLASTIC, BLACK (1.5 m wide) m 18.00


PLASTIC, TRANSPARENT (1.5 wide) m 10.00


CEMENT PORTLAND TYPE 1 (42.5 kg) BAG 12.80

544.00 Camion Pacasmayo 449



SAND, COURSE m3 0.53

1600.00 843.76 Camion Morropon 45.5

SAND, FINE m3 0.83

1600.00 1328.00 Camion Morropon 45.5

STONE, 1/2" TO 3/4" m3 1.11

2515.00 2826.25 Camion Morropon 45.5

MIXED AGGREGATE, SAND AND STONE m3 0.07

1922.00 included in other


WIRE, BLACK No. 16 kg 2.10




DRY GRASS BUSHEL 1.00

20.00 N/A Local 0

CHICKEN WIRE (1x1 cm) m 1.00


TUBE PVC 1/2" 5 m UNIT 6.00




TEE PVC 1/2" UNIT 6.00


ELBOW PVC 1/2" UNIT 5.00


COUPLING 1" TO 1/2" (GAS EXIT) UNIT 3.00


NIPPLE FOR HOSE CONNECTION 1/2" TO 3/8" UNIT 5.00


HOSE, GAS 3/8" m 7.00


HOSE CLAMP 3/8" UNIT 5.00


79



HOOKS FOR TUBE 1/2" BAG 5.00


VALVE 2" UNIT 1.00


REDUCTION PVC 6" TO 4" UNIT 1.00


STOVE, TABLE TOP 2 BURNERS UNIT 1.00


NAILS, MIXED kg 2.00




ETERNIT ROOF, GRAY 8" UNIT 2.50 8.96E-03 1300.00 29.13 Camion Lima 1108

PLYWOOD ft2 30.49 0.0014 670.00 - Camion Piura 130


HINGE 3" UNIT 3.00


DOOR KNOB UNIT 1.00
















PLASTER 16kg BAG BAG 0.29












TUBE, PVC 4" m 7.21




80









TEE PVC SAL 4" x 2" UNIT 1.00


"Y" PVC 4" UNIT 1.00


Table A.9: Material inventory for biodigester latrine brick corrugated metal privacy structure


REACTOR 10m3 (8x1.42 m) GEOMEMBRANE 0.6 mm thick UNIT 1.00 2.24E-02 1400.00 34.00 Camion Lima 1108

GAS RESERVOIR (2.2x0.9 m) UNIT 1.00 4.50E-03 1400.00 10.00 Camion Lima 1108

PLASTIC, BLACK (1.5 m wide) m 18.00


PLASTIC, TRANSPARENT (1.5 wide) m 10.00


CEMENT PORTLAND TYPE 1 (42.5 kg) BAG 15.80

671.50 Camion Pacasmayo 449



SAND, COURSE m3 0.53

1600.00 843.76 Camion Morropon 45.5

SAND, FINE m3 0.83

1600.00 1328.00 Camion Morropon 45.5

STONE, 1/2" TO 3/4" m3 1.11

2515.00 2826.25 Camion Morropon 45.5

MIXED AGGREGATE, SAND AND STONE m3 0.07

1922.00 included in other






DRY GRASS BUSHEL 1.00

20.00 N/A Local 0

CHICKEN WIRE (1x1 cm) m 1.00


81



TUBE PVC 1/2" 5 m UNIT 6.00




TEE PVC 1/2" UNIT 6.00


ELBOW PVC 1/2" UNIT 5.00


COUPLING 1" TO 1/2" (GAS EXIT) UNIT 3.00


NIPPLE FOR HOSE CONNECTION 1/2" TO 3/8" UNIT 5.00


HOSE, GAS 3/8" m 7.00


HOSE CLAMP 3/8" UNIT 5.00


HOOKS FOR TUBE 1/2" BAG 5.00


VALVE 2" UNIT 1.00


REDUCTION PVC 6" TO 4" UNIT 1.00


STOVE, TABLE TOP 2 BURNERS UNIT 1.00


NAILS, MIXED kg 2.00


BAMBOO, 4 m UNIT 4.00

Camion Piura 130



PLYWOOD ft2 30.49 0.0014 670.00 - Camion Piura 130


HINGE 3" UNIT 3.00


DOOR KNOB UNIT 1.00
















82



PLASTER 16kg BAG BAG 0.29












TUBE, PVC 4" m 7.21








TEE PVC SAL 4" x 2" UNIT 1.00


"Y" PVC 4" UNIT 1.00


83

Appendix B LCA Results Data Table B.1: LCA results for construction and use phase of VIP latrine adobe fiber cement privacy structure

Construction phase Unit Input

CED (MJ)

GWP (kgCO2 eq)

Brick, at plant/RER S kg 1,420.7 4,019.7 337.9

Transport, lorry 3.5-16t, fleet average/RER S kgkm 182,581.9 751.2 43.2

Portland cement, strength class Z 42.5, at plant/CH S kg 106.3 403.5 87.3

Fibre cement corrugated slab, at plant/CH S kg 29.1 267.6 19.9

PVC pipe E kg 1.4 92.4 4.4

Plywood, outdoor use, at plant/RER S m3 1.40E-03 49.6 0.9

Sawn timber, softwood, planed, air dried, at plant/RER S m3 3.78E-03 40.9 0.3

Steel rebar, blast furnace and electric arc furnace route, production mix, at plant GLO S kg 5.0 53.5 5.2

PVC (emulsion polyerisation) E kg 0.3 17.2 0.8

Iron and steel, production mix/US kg 1.6 16.6 1.4

Sand, at mine/CH S kg 80.0 4.6 0.2

Gravel, round, at mine/CH S kg 75.5 4.4 0.2

Stucco, at plant/CH S kg 1.6 2.3 0.1

Adobe brick kg 4,090.8 - -

Total construction phase 5,723.6 501.8

Use phase





PVC pipe E kg 1.4 92.4 4.4






Sand, at mine/CH S kg 80.0 4.6 0.2




84

Appendix B (Continued) Table B.1: (Continued)

Carbon dioxide (100% anaerobic) kg 1,401.4 - 1,401.5

Methane (100% anaerobic) kg 509.6 - 12,740.5

Total use phase (100% anaerobic) 5,723.6 14,643.7




Total (100% anaerobic) 11,447.1 15,145.5

Total 50% anaerobic) 11,447.1 8,642.2

Table B.2: LCA results for construction phase of VIP latrine brick corrugated metal privacy structure


CED (MJ)

GWP (kgCO2 eq)


Transport, lorry 3.5-16t, fleet average/RER S kgkm 358,860.2 1,588.7 126.9


Galvanized steel sheet, at plant/RNA kg 10.03 297.3 27.2

PVC pipe E kg 1.36 92.4 4.4

Plywood, outdoor use, at plant/RER S m3 0.0014 49.6 0.9

Sawn timber, softwood, planed, air dried, at

plant/RER S m3 0.00378 40.9 0.3

Steel rebar, blast furnace and electric arc furnace

route, production mix, at plant S kg 5.03 53.5 5.17



Sand, at mine/CH S kg 80 4.6 0.2



Total construction phase 11,668.2 1,083.7

85

Appendix B (Continued) Table B.3: LCA results for construction phase of VIP latrine adobe fiber cement (unlined pit) privacy structure


CED (MJ)

GWP (kgCO2 eq)



PVC pipe E kg 1.36 92.4 4.4




plant/RER S m3 0.00378 40.9 0.3


route, production mix, at plant GLO S kg 5.03 53.5 5.2


Steel, billets, at plant/US kg 1.6 16.6 1.4




Adobe brick kg 4090.8 - -

Total construction phase 760.4 58.4

86

Appendix B (Continued) Table B.4: LCA results for construction and use phase of pour-flush latrine adobe fiber cement privacy structure


CED (MJ)

GWP (kgCO2 eq)



Portland cement, strength class Z 42.5, at /CH S kg 531.3 2,017.7 436.3

Sanitary ceramics, at regional storage/CH S kg 45.2 1,941.6 105.7

PVC pipe E kg 7.7 523.9 24.9


Gravel, round, at mine/CH S kg 4,888.3 283.1 11.7


Sand, at mine/CH S kg 4,046.0 234.3 9.7

Sawn timber, planed, air dried, at plant/RER S m3 1.55E-02 167.6 1.3

PVC injection moulding E kg 1.1 105.2 3.2



Bronze, at plant/CH S kg 0.6 30.3 1.7

Gypsum plaster (CaSO4 hemihydrates) DE S kg 4.7 16.9 1.1

Pre-cast concrete, min. reinf., prod. mix, concrete type C20/25 RER S kg 20.0 13.2 2.4



Use phase


Portland cement, strength class Z 42.5, /CH S kg 106.3 403.5 87.3









Total (100% anaerobic) 18,464.4 15,788.8

Total (50% anaerobic) 18,464.4 9,285.5

87

Appendix B (Continued) Table B.5: LCA results for construction phase of pour-flush latrine brick corrugated metal privacy structure


CED (MJ)

GWP (kgCO2 eq)





PVC pipe E kg 1.36 92.4 4.4



plant/RER S m3 0.00378 40.9 0.3


route, production mix, at plant S kg 5.03 53.5 5.17







88

Appendix B (Continued) Table B.6: LCA results for construction and use phase of composting latrine adobe fiber cement privacy structure


CED (MJ)

GWP (kgCO2 eq)



Portland cement, strength class Z 42.5, at plant/CH S kg 382.5 1,452.7 314.1


PVC pipe E kg 9.5 643.5 30.6


Polypropylene injection moulding E kg 3.6 418.1 15.8

Gravel, crushed, at mine/CH S kg 2,150.3 296.7 9.4



PVC injection moulding E kg 1.0 95.6 2.9



Plywood, outdoor use, at plant/RER S kg 1.40E-03 49.6 0.9



Total construction phase 11,274.7 943.0

Use phase without Resource Recovery

Carbon dioxide kg 1,135.4 - 1,135.4

Methane kg - - -

Use phase with Resource Recovery


Methane kg - - -

Fertilizer use avoided (N) kg 442.6 -29,332.9 -1,462.2

Total without Resource Recovery 11,274.7 2,078.5

Total with Resource Recovery -18,058.2 616.2

89

Appendix B (Continued) Table B.7: LCA results for construction phase of composting latrine brick corrugated metal privacy structure


CED (MJ)

GWP (kgCO2 eq)





PVC pipe E kg 9.5 643.5 30.6


route, production mix, at plant GLO S kg 31.5 335.0 32.4


Gravel, crushed, at mine/CH S kg 2,150.33 296.7 9.4



plant/RER S m3 0.0235 254.0 2.0

PVC injection moulding E kg 1 95.6 2.9



Plywood, outdoor use, at plant/RER S kg 0.0014 49.6 0.9



90

Appendix B (Continued) Table B.8: LCA results for construction and use phase of biodigester latrine adobe fiber cement privacy structure


CED (MJ)

GWP (kgCO2 eq)


Polyvinylchloride, bulk polymerised, at plant/RER S kg 44.0 2,665.2 87.3



Brick, at plant/RER S kg 608.9 1,722.8 144.8

PVC pipe E kg 12.7 860.9 41.0

Sawn timber, softwood, planed, air dried, at plant/RER S m3 0.1 669.2 5.3

Polyethylene low density granulate (PE-LD), production mix, at plant RER kg 8.3 614.5 17.5






Gypsum plaster (CaSO4 alpha hemihydrates) DE S kg 4.7 16.9 4.9



Pre-cast concrete, min. reinf., prod. mix, concrete type C20/25, w/o consideration of casings RER S kg 20.0 13.2 2.4



Use phase general Polyvinylchloride, bulk polymerised, at plant/RER

S kg 81.8 4,957.2 162.5


Use phase without Resource Recovery


Methane kg 1,757.0 - 43,925.8

Total use phase without Resource Recovery 5,362.4 48,571.6

Total without Resource Recovery 19,989.9 49,655.2

91

Appendix B (Continued) Table B.8: (Continued)

Use phase with Resource Recovery


Methane kg - - -

Natural gas use avoided m3 2,473.7 -95,324.7 -810.9

Fertilizer use avoided (N) kg 2,382.0 -157,864.8 -7,869.4

Total use phase with Resource Recovery -247,827.1 798.6

Total with Resource Recovery -233,199.6 1,882.2

Use phase without Resource Recovery with

Flaring


Methane kg - - -

Total use phase without Resource Recovery with Flaring 5,362.4 9,478.8

Total without Resource Recovery with Flaring 19,989.9 10,562.4

Table B.9: LCA results for biodigester latrine brick corrugated metal privacy structure


CED (MJ)

GWP (kgCO2 eq)



Polyvinylchloride, bulk polymerised, at plant/RER S kg 44 2,665.2 87.3



PVC pipe E kg 12.67 860.9 41.0


plant/RER S m3 0.0619 669.2 5.3

Polyethylene low density granulate (PE-LD),

production mix, at plant RER kg 8.34 614.5 17.5





Steel, billets, at plant/US kg 9.02 102.2 8.8



Gypsum plaster (CaSO4 alpha hemihydrates) DE S kg 4.71 16.9 1.1

Pre-cast concrete, min. reinf., prod. mix, concrete

type C20/25, w/o consideration of casings RER S kg 20 13.2 2.4



92

Appendix C Permissions C.1 Cairncross and Feachem (1993) Permission

C.2 Buckley et al. (2008) Permission

C.3 Mihelcic et al. (2009) Permission

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